Modifying the PRM80 series radios
Author: Michel G Mitaux Version: 10.1 (July 2003)
Original of this document can be found at: www26.brinkster.com/mitaux80/index.html and at www.geocities.com/ch8users/ (updated less frequently at this location, but also has info on other two way radios, and scanning info for Australia)
email: mitaux8030@hotmail.com
I am always impressed with Philips radios. I think that they are sensibly designed, both from an operation & design standpoint, they perform well, and are quite reliable. Philips, then Simoco who took over the radio business of Philips, and more recently with "ComGroup" (the result of Simoco dividing into two distinct 'streams' - the now defunct Simoco concentrated on TETRA, and ComGroup in Australia at least does the normal PMR stuff now) and most recently with TMC (what Philips used to be known as in the beginning) reforming, produced many commercial two way radios for use by industry, business & emergency services. Philips also produced CB radios, though these products nowadays are not as prolific as their commercial equipment.
As far as the hobbyist is concerned, Philips produced both 27 MHz and 477 MHz CB radios. (A note for our non-Australian readers: Australia has two CB bands - the 27MHz band of 40 channels between 26.965 MHz and 27.405 MHz, with AM and SSB modes permitted, and the unique-to-Australia UHF CB band, also of 40 channels between 476.425 MHz and 477.400 MHz in FM mode, with semi-duplex repeater operation allowed on channels 1-8 as the outputs, and 31-38 as the inputs. New Zealand also has a similar UHF service on the same frequencies) Indeed, if it were not for Philips, UHF CB repeaters and even the whole UHF CB concept might never have existed today. With the exception of the ill-fated FM321, Philips have not, as far as I know, produced a radio designed for amateur use; not that this matters for much, their fine commercial two-way radios convert nicely for amateur use, and also for those looking for something a little bit different to use on the UHF CB band, too.
In recent times (well, maybe not so recent) the following Philips commercial radios have found their way into hobbyist radio enthusiasts eager hands:
FM828 - a crystal controlled, 1 to 10 channel unit, remote head or single piece that was popular during the 1970s. They are still around today, and are easy to convert into repeaters, but lack somewhat in style & features, and modern day radio designs have the edge on sensitivity and selectivity these days, but the good 'ol FM828 won't embarrass itself.
FM900 - Very popular synthesized 10, 99 or 120 channel units, remote head or single piece units, with various features & options like scanning, Selective Calling (SelCall) and CTCSS, voting and so on. Near bulletproof physical construction (except the dreaded VCO blocks!), very good performance and easy to operate. Popular with the amateurs on 2 metres, 70cm and with some work, the 70 MHz VHF versions can be converted to 6 metres. Also popular with the UHF CB brigade who want something that little bit special: maybe 25 watts (which is of course illegal on UHF CB) or something that will transmit 5 watts all day long without getting stressed, or maybe chosen for the excellent manners exhibited when faced with an interference laden spectrum. At first, the W1 band (470-490 MHz) radios were the units of choice for CB, but it didn't take too long to discover that the U band (450-470 MHz) or the W4 band (490-520 MHz) units could stretch their legs into the 477 MHz CB band with a bit of encouragement. Someone had also managed to 'hack' the Field Personality Programmer (FPP), the software used to program the RF frequencies / channels and other features onto EPROM for the FM900, enabling the radio to receive frequencies outside the normal designated band of the unit, or to enable 25 watts on UHF CB. The original FPP software didn't allow the radios to venture outside their normal frequency limits, or allow high power operation on UHF CB.
And now we come to the PRM80 units. These are more modern day units (circa 1989) which offer a plethora of features all customisable with software, remote head or single piece units, 10, 64, 100 or 200 channel units, and trunking variants were available, too. Alphanumeric channel names were available on one model, the 8040. All this in a radio that is somewhat smaller & lighter than the FM900, modern-day styling, highly interference resistant and very sensitive to weak signals. The PRM80 series of radios has only recently been replaced by the Simoco 9000 series radios, though the PRM80 series continues to be supported.
The PRM80 family consists of:
*PRM8010 - a local mount only, 10 channel version with a single digit display (two digits for the trunked version) and only four function buttons, CTCSS and fixed SelCall system.
Was also known as Mobria R20 in Scandinavian countries.
*PRM8020 - a local mount only, 64 channel version with 4 digit display, eight function buttons, CTCSS and variable SelCall system, and scanning
Was also known as Mobria R21 in Scandinavian countries.
*PRM8025 - a local mount only, 100 channel version with 6 digit display, eight function buttons, CTCSS and variable SelCall system, and scanning and voting
*PRM8030 - a remote mount, 100 channel version with either 4 digit remote head or optional 6 digit remote head, eight function buttons, CTCSS and variable SelCall system, DTMF and scanning and voting
*PRM8030 Dual Mode - same as the PRM8030, but additionally can have two trunking networks programmed in (the trunked network feature is not much use to us hobbyists, even for receive only, since the unit must 'register' with the network)
*SRM8038 - like the PRM8040 (and uses the same main unit) with an alphanumeric display with keypad, similar but slightly fewer features, more modern styling.
*PRM8040 - a remote mount, 200 channel version, with alpha-numeric display remote head, function & full keypad built in, CTCSS and variable SelCall with memory list, DTMF, scanning and voting. Top of the line PMR unit, produced only in Australia
*PRM8041 Dual Mode - same as the PRM8040, but can have trunking networks programmed in as well as the PMR channels.
UK models:
*8060 Band 3 (175-220MHz) trunked visually identical to 8010
*8070 ditto 8060 but like 8020
*8061 data mobile without display for such as Fire Service mobilising, mainly E-band (68-88MHz)
E0 = 66 to 88 MHz
B0 = 132 to 156 MHz (not common in Australia)
A9 = 146 to 174 MHz
K1 = 174 to 208 MHz (not common in Australia)
KM = 223 to 235 MHz (not common in Australia)
R3 = 330 to 400 MHz (not common in Australia)
TM = 400 to 440 MHz
TU = 403 to 470 MHz
T4 = 425 to 450 MHz (not common in Australia)
U0 = 440 to 470 MHz
UW = 450 to 520 MHz
W1 = 470 to 500 MHz
W4 = 494 to 520 MHz
X = 800 MHz trunking bands (not common in Australia)
Dedicated trunking units are also available, but are not much use to us in this form.
They can not be used as standard two-way radios (i.e. PMR mode), although I have shown that with replacement of the firmware EPROM, they can be used as a normal PMR radio. Other mods are required (0 ohm SMD resistor jumpers) to enable SelCall signaling. Models included 8025T (curiously labeled as 8020T), 8030T, 8041T, 8042T, 8060T, 8070T, and supposedly a model that looks like an 8010. Certainly a dual mode unit can be transformed into a single mode unit by replacement of the EPROM and altering some jumpers - not that there is much point in doing this, because the dual mode units can be programmed in PMR mode anyway.
Various options are also available, such as:
*6 digit local or remote heads - used to upgrade a PRM8030 or 8020T from a 4 digit head
*DTMF microphone - can be connected to any of the PRM80 family to transmit
DTMF tones, useful for those radios that does not have built-in DTMF capability.
*Controller (keypad) microphone - looks almost identical to the DTMF microphone,
but can be used to obtain extra functions on the radio, and directly enter SelCall numbers etc. This microphone will only work on 6 digit heads (i.e. 8025 or 8030 with the optional 6 digit head)
*Power supply & console unit (for 'base station' use)
*Power supply & remote console unit for remote control base station use.
*Modem card (for transmission of data, and programming the radio personality)
*voice synthesizer card for trunking operation
*quick release mounting bracket
*cross band repeater cable kit
*hands free microphone set up
*covert microphone
*telephone style handset
*transportable kit
*alternate speakers
*numerous outboard options - MAP27 data interface, GPS & AVL systems, etc etc
*and plenty of other options I wouldn't even know about
What would you say if I told you that you can buy a PRM80 in a band that nobody (almost!) wants e.g.: a E band 70 MHz or W4 band 500-520 MHz for a song (try $100 to $150), and modify it to any band you want? Alternatively, buy a faulty PRM80, one that doesn't transmit or receive, and have a high probability that you can repair & modify it using the same magic? If you are experienced in soldering and have some knowledge on radio theory, it's pretty easy, and in the process you will save some serious money. And you will learn a bit, too. Be warned, however, this is no 'snip a diode' mod - it is a full on retune in some cases, and you will need some knowledge on the generic inner workings of modern radio circuits and tune up & appropriate test equipment.
Before diving into the modification info, lets learn a bit about the design of the PRM80. Firstly, the PRM80 can be divided up into three discrete electronic sections: the display & user interface, the RF board (both RX & TX) and the systems & control board. The RF board seems to be common to all models, for example, if you buy a U band PRM8010, 8020, 8025, 8030 & 8040, you will find that they all share the same RF board (well, not quite, but close enough for most of our purposes; the RF boards from most 8010s and 8020s could not handle voting or RSSI; that is a received signal strength indicator). Not only that, but the interface between the control board and the RF board is common no matter what frequency band unit you get. This opens up the possibility of getting a VHF unit, and replacing the RF board with a UHF one, and getting the radio up and operating on a UHF band. Or it can be done the other way round to get a unit capable of operating on the 2 metre band. Not only that, but you can also get a U band (be careful, see more below) or a W4 band unit, and get it to operate on UHF CB. And just like the FM900 hacked software, you can also program out of band frequencies or high power on UHF CB channels for the PRM80 as well. Lets cover the simple conversions first, introducing various 'tricks' and concepts, working our way up to more complicated conversions. Even if you are not interested in getting your PRM80 onto the 2 metre amateur band for example, it is suggested that you read all sections anyway, because each section details something useful or some operation that may be required for another conversion which you may be interested in. Let's begin:
The A9 band to 2 metre (144MHz) amateur conversion:
If you are looking to get a PRM80 for 2 metre amateur operation, buy an A9 (146-174 MHz) band PRM80, then all you need to do is to re-program the hardware code to make the unit think it is a B0 (132-156 MHz) band unit, and then directly program the required 2 metre frequencies. This task is easy on a PRM8030 or 8025, since the software that you use to program the frequencies and generally customise the radio also has the ability to change the hardware code. To do this for the 8030 or 8025, follow these steps:
1) Using FPP, read the present configuration from the radio, and save it as a file. That way, if things go wrong, you can set your radio back to the way it was and start over.
2) Take note of your hardware code.
3) Disconnect the programming interface cable from the radio, and start a new job, selecting a hardware code that is as close as possible to the one you already have, but this time in the B0 band. For example if you had a 9525 001 10840, you would choose a 9525 001 10841.
4) Program your radio as desired, then write the configuration to the mobile. After a second or two, FPP will ask you to confirm change of the hardware code - answer 'yes'.
For the 8010 or 8020, if you want to change hardware codes, you will need to run the prm80hw.exe program, enter a valid 12NC number (which is discussed below in the section "8010 & 8020 hardware codes", then press F4 to program the radio with the new hardware code, then program the channels, frequencies and other options from scratch with the prm80sw.exe software.
Of course, if you only want access to frequencies above 146 MHz, then keeping the radio as an A9 band is easiest. Or, you could even fiddle around with the out-of-band frequency programming detailed below to get access to frequencies below 146 MHz even if the unit is still programmed as an A9 band unit. Re-tuning the receive front end filters, TX and RX VCOs will be necessary for optimum performance. Tuning the VHF front end is carried out using the following procedure:
1) Select the channel for the highest receive frequency, and set up a RF signal generator to this frequency at 50uVpd
2) Adjust R557 (and R554 if needed) for 18.0 VDC +0 / -1 V at TP403
3) Using a CRO (AC coupled) probe pin 2 of U401, and adjust the tuning cores of FL400 and FL401 for maximum waveform level on the CRO, reducing the input RF signal if the observed waveform stops increasing. The waveform is going to be pretty small, and is 455kHz in frequency.
4) Select the channel for the lowest receive frequency and set the RF signal generator to that frequency
5) Adjust R554 for maximum observed waveform level on the CRO
6) Select the channel for the highest receive frequency, and set the RF signal generator to this frequency (again)
7) Re-adjust R557 for maximum observed waveform level on the CRO. Only a slight adjustment of R557 should be needed.
8) Repeat steps 4 to 7 again
9) Disconnect RF signal generator, open (disable) mute, and adjust L404 for maximum audio output. Then using an off-air signal, preferably one that is a little weak, adjust L404 for minimum distortion.
Tuning the VCOs is fairly easy for VHF - the procedure is reproduced here for your information:
VHF receive VCO:
1) Select the channel for the highest receive frequency
2) Adjust L407 for 15.0 VDC +/- 0.2 V at TP402
3) Select the channel for the lowest receive frequency
4) The voltmeter reading at TP402 should be somewhere between 5 and 13 VDC
VHF transmit VCO
1) Select the channel for the highest transmit frequency and activate PTT
2) Adjust L445 for 15.0 VDC (A or B band) or 16.0 VDC (E band) both +/- 0.2 V at TP402
3) Release PTT, select the channel for the lowest transmit frequency, reactivate PTT
4) The voltmeter reading at TP402 should be somewhere between 3 and 5 volts
If in step 4 for both RX and TX the voltage measured is higher than the range indicated, don't worry too much, so long as the unit has stable RX & TX at the highest & lowest frequency channels. I found it easier to tune the VCO (both TX & RX) for 6 volts at 144 MHz when programming & tuning for the two metre band, since it is not possible to obtain any more than 10 volts at TP402 at 148 MHz or so.
Tuning the reference oscillator is easy: select a mid-frequency transmit channel, activate the PTT and adjust L411 (or the trimcap visible in the TCXO module for those that have the higher stability oscillator) for the correct frequency +/- 500 Hz. Don't forget to re-do this adjustment after you have refitted the RF shield.
The U band to UHF CB conversion:
Similarly, if you want a UHF CB PRM80, you can buy a U band unit, reprogram the hardware code as a W1 band unit, and program the UHF CB frequencies you need. Just follow the procedure above for the A9 band to B0 band conversion. With the U band pulling up to W1 band, you will loose some sensitivity, however, and if you want to later fool the radio into high power TX, then you may suffer from TX instability. An alternative to this is to simply program in the UHF CB frequencies using the out of band frequency entry procedure detailed below. This method would probably be the safer of the two, but will not overcome the possible lack of TX stability or loss of RX sensitivity.
Caution: Sometimes a U band unit just simply won't operate at UHF CB frequencies at all, due to the VCO simply not wanting to budge an inch (kilohertz?) above 470 MHz. I have found that the U band units can mostly be encouraged up to 474 or 475 MHz, but not much further. If there is an easy but reliable 'bodge' job fix for this, then I'd be interested to hear from you...
It is possible to modify the RX VCO resonator (and you will need to do something similar to the TX VCO resonator, too) to shift it's coverage up slightly, maybe 2 or 3 MHz, by very carefully desoldering and extra carefully removing the centre 'plunger' from the resonator, and 'shortening' the loop on the plunger by filling in some of the loop with solder, only 1 or 2mm at most, and filing the same amount off the end. Then re-insert the shortened plunger and solder as you found it. This may just give you enough coverage to operate a U band unit at UHF CB, but results will vary slightly from radio to radio.
If you want to raise the frequency of operation further, you will need to desolder the entire resonator and shorten both the centre plunger and the resonator body itself - and because the body is made of ceramic with a solder substrate coating, this would be an enormous amount of work and I think it would be easier to buy a RF board in the band you need.
Another thought would be to use a very fine file to shorten the resonator in-situ. Because of the surrounding components and proximity of the PCB at the bottom, you might need to do this at an angle, but doing so I'm sure would reduce the Q of the resonator. I wonder if a 'Dremel' tool with a sanding / grinding / polishing disc or other bits could get in there and shorten the resonator at a nice right angle? You could then paint some sort of conductive paint over the end of the resonator to complete the job. I have seen a 'liquid solder paint' that adheres to ceramic that looks ideal for this. These are just my ideas - I'm not brave enough to actually try them out! If someone does have a go at this, let me know the results...
Yet another thought could be to remove or substitute one of the small fixed value surface mount capacitors (not any of the black varicaps) that sit near each of the resonators. I am not sure exactly which capacitors you would need to modify, and it may not be possible to achieve very much 'pull'. Obviously you will need a circuit diagram to determine which capacitors would be best to achieve this. Again, this is just my thoughts, and I have not attempted this procedure. Again, if someone does have a go at this, let me know!
The W4 band to UHF CB conversion:
My favourite! Re-programming a W4 band unit into thinking it is a W1 band follows the very same procedure outlined above. However, this time, there are things you can do to improve the performance of the W4 RF board at the lower frequencies. Just re-programming the unit from a W4 to W1 band does not work for frequencies below about 485 MHz (or at least that's what I found), so you will need to do this: buy seven 'R4001' 2 to 7pf trimmer capacitors from Altronics (www.altronics.com.au or phone 08 9328 1599 in Australia), and solder these capacitors across the seven resonators of the RF board: 5 front end resonators, 1 RX VCO resonator, and one TX VCO resonator. Actually, buy about 10 lots of R4001 - sometimes the legs of the trimcaps where they pass through the ceramic substrate either break, or have unreliable joins to the capacitor plates and this is not easy to fix or repair (it can be done, but you need to be pretty good on the soldering iron - fast, accurate, and as little extra solder as possible, but that liquid solder paint I spoke of just above would probably do just as well)
When purchasing your R4001 trimcaps, do try to make sure that they are indeed R4001 types (2-7pF). These have a splash of red paint on the top. Look-a-likes and other colour paint markings should be rejected, since they are probably not 2-7pF. Likewise, other versions of 2-7pF or similar value, such as the Dick Smith R2940 or R2935 (there might be others from Jaycar etc) should all be left alone. They are not physically small enough to do the job. I have found a few alternatives from RS components: 1.5 to 6pF part no 247-0372, $1.67 ea; or
2.8 to 12.5pF part no 247-0388 also $1.67 ea; or
1.4 to 3.0pF surface mount part no 832-295, $2.87 ea; or
2.0 to 6.0pF surface mount part no 832-302 also $2.87 ea; or
3.0 to 10.0pF surface mount part no 832-318 again $2.87 ea.
For parts from RS components, you need to buy them in lots of 5; ie you can buy 5 or 10 or 15 and so on.
Now that you have your R4001's, soldering across the resonator means to solder one leg of the trimcap to the centre connection of the resonator, preferably near where the centre of the resonator is soldered to the PCB and the other leg of the trimcap goes to the top outside of the resonator, which is earthed. Be careful when orienting the trimcap to keep the trimcap profile low so that the metal RF shield doesn't short out on the trimcap when in place. Also be careful that the trimcap doesn't short out on the edge of the resonator or other components of the PCB. Be neat with your soldering, and use the minimum amount to form a good joint - too much solder (or heat!) can adversely affect the resonators performance. A very fine tip soldering iron is a must - if you have to go out and buy a tip specially for this job, do it! And handle the trimcaps very carefully - they are very fragile.
Tuning the trimcaps is the next step. This process is made much easier if you have access to a signal generator and spectrum analyser, but with copious amounts of persistence, you should be able to tune them without those luxuries. You will need a non-metallic tuning wand / adjuster for this task, I recommend a ceramic blade screwdriver. Get one if you don't have one, or you will prematurely loose all your hair! You will also need to find some short screws with a matching thread to temporarily but securely hold down the RF board to the chassis. You will get variable results otherwise during the tuning process. Be careful not to over tighten the screws - they may strip or shear off causing problems later. Just tighten them firmly.
Start with the RX VCO resonator (the one by itself closest the centre of the RF board near the front end resonators) - start by setting the radio to the highest receive frequency channel, and tune the RX VCO trimcap so that a strong Local Oscillator (L.O.) is visible at the correct frequency on the spectrum analyser, or is audible on a scanner receiver at the correct L.O. frequency (which will be your receive frequency minus 21.4 MHz exactly). Repeat this procedure for your lowest receive frequency. Check that the highest receive frequency LO is still being generated for this setting. If not, go back and forth between the highest & lowest receive frequency channels, very carefully adjusting the RX VCO trimcap (and R554 if absolutely necessary) for correct & on-frequency generation of the L.O. If you select your frequencies too far apart, the VCO may not be able to cope! Having said that, my conversions have in each case been able to span 460 MHz to 490 MHz RX quite happily - not bad for a board originally designed for 494-520 MHz. If you are very careful with your tuning and have made good, neat solder joins with your trimcaps, your VCO for RX can span 38 or maybe 40 MHz. Again, use a non-metallic screwdriver to adjust R554 & R557.
The second series of adjustments is to tune the trimcaps that you have placed on the five front-end receive resonator filters. Normally, on UHF at least, the resonator filters are broad enough by themselves, along with varactor frequency-tracking to cover the original band intended. Here we are adding some capacitance across the resonators to lower their overall frequency of operation. Because each filter is now individually tunable, you will be able to make the front end a little more sensitive, at the expense of being slightly less broadband. Not that this is a marked effect - after tuning for a centre RX frequency of 473 MHz, I found that there was only about 1dB performance loss at 465 & 480 MHz (your mileage may vary, of course). The procedure for tuning the front end trimcaps is similar to the one listed above: choose the frequency at which is either in the middle of your desired coverage, or the frequency at which you want absolute maximum sensitivity, then put a stable but weak signal into the receiver (don't forget to do this on a non-CTCSS channel, and disable the mute) so that it is just audible. Then tune each trimcap starting with the one nearest the antenna connector and moving to the front of the unit, in each case tuning for minimum noise. If the signal becomes largely noise-free, then decrease the input signal again so a moderate amount of noise is apparent. Always tune for minimum noise using the weakest input signal possible. Another more scientific way is to observe the waveform at U401 pin 2, which is proportional to the received signal strength.
Once this has been done, tune the tiny pair of variable resistors which set the tracking gain & VCO offset, following the procedure as detailed in the service manual:
1) Select the channel for the lowest receive frequency
2) Set a RF signal generator to this frequency, at 50uVpd (or more if needed to get an audible signal), and connect to the antenna connector.
3) Using a CRO (AC coupled, 10uS per div, and the waveform will be pretty small; 50 to 100mV or so, at 455 kHz), probe across pin 2 of U401, and adjust R554 for maximum observed waveform level
4) Select the channel for the highest receive frequency, and reset your RF signal generator to this frequency
5) Adjust R557 for maximum observed waveform level on the CRO
6) Repeat steps 1-4 again
7) Disconnect RF signal generator, open (disable) mute, and adjust L404 for maximum audio output. Then using an off-air signal, preferably one that is a little weak, adjust L404 for minimum distortion.
In rare cases, you may have to go back and forth between tuning the RX VCO trimcap and the above procedure for R554 & R557 to get a relatively stable VCO operation over all your chosen frequencies. As a final check, listen to the L.O. on a scanner receiver - if it sounds noisy (kind of like a rushing, windy noise), continue tuning. A spectrum analyser helps greatly with setting up the RX VCO, but with lots of time & patience, you can get by with just a scanner receiver. Also note that if you are trying to get your receiver to cover more than 20 MHz, the tracking gain adjustments may not work quite as expected, giving good sensitivity at the edges of the band, but poor sensitivity in the middle. If this happens, you will just have to fiddle to arrive at a suitable compromise.
If you are really searching for maximum sensitivity on one particular frequency, go through tuning the trimcaps one more time at that frequency. Otherwise, you have now adjusted the radio for very good sensitivity across the bandwidth. Normally, for a W4 band board modified as such will produce a minimum detectable signal of slightly less than 0.10 uV (i.e. one really hot receiver), and minimum mute threshold of 0.12 to 0.15uV.
(Hint: you can use a 'low tech' scanner as a signal generator - all you need to do is to tune the scanner to your desired frequency + the scanner's first I.F. So, if you wanted to generate a test signal at 470.000 MHz, and your scanner uses a 10.7 MHz I.F., then tune the scanner to 480.700 MHz, and you should then have a weak signal being generated at 470.000 MHz courtesy of the scanners own local oscillator. If no signal is heard, also try 10.7 MHz below the desired frequency: in the above example try programming 459.300 MHz on the scanner. Most 'low tech' scanners use either 10.7, 10.8, 10.85 or 21.4 MHz I.Fs. Locate the scanner a suitable distance away from your radio under test to achieve a suitably weak signal. This method is not without it's drawbacks however; any hand, arm or body movement can alter the received strength on your radio, as can other people walking nearby, etc etc but with some practice, you should be able to tune the radio quite well)
The last adjustment to be made is for the TX VCO filter. All you need do is tune to the highest & lowest TX frequency channels, and tune the trimcap on the TX VCO filter resonator (the resonator all on its own, on the opposite side of the RF board to the RX section) for maximum TX stability. If you find that at first this doesn't appear to be possible, the TX VCO will need really fine adjustment to achieve stable TX across your chosen frequencies, so persist with it. Keep in mind that the TX VCO & buffer stage that you are tuning needs to be shielded normally. Because of this, it is critical that you have the screws in place holding down the PCB to the chassis in the vicinity of the TX VCO resonator filter. Sometimes this is not enough, and you will need to use your finger to push down on the PCB edge near the TX VCO resonator filter to ensure good earthing contact with the chassis during tuning. If you do experience a problem, it will manifest itself as either no TX at all, or a fast pulsing TX, especially on key-up. I have found it easier to do any initial tuning on low power, then do final adjustments on high power. Of course, during this stage, always transmit in to a good dummy load. You should be able to get your unit to TX across a span of about 35 MHz if required. Don't forget to 'stress test' your transmitter - key the transmitter up for about 1 minute at a time, then let it rest for another minute, and repeat this process until the radio is reasonably warm (not hot!) - if you find that your upper or lower channels are not transmitting or receiving after this, it probably means your tuning of the respective VCO wasn't quite centred in your chosen bandwidth. VCOs do things like this when they get warm, so it's best to check and adjust accordingly now while you have the radio apart, rather than find out during a lengthy conversation that you hadn't centred the VCO tuning.
Be careful with the tuning of the trimcaps - they are very fragile, and because the trimcaps have no 'stops' in the adjustment, that is their adjustment goes around and around forever, you will find two tuning 'peaks' and either peak should theoretically work, but practically, because the trimcap is usually very close, if not hard up against the metal shield, one 'peak' may work out better than the other. It reaffirms my thoughts that you do need to have a bit of RF knowledge when tuning these critters, which is made so much easier with 'real' test equipment like a sig-gen and CRO etc.
Obviously, it will be easier to tune up a modified PRM80 if you restrict it's frequencies to a narrow range i.e. UHF CB only (and you will get very slightly improved sensitivity, too). The tuning becomes slightly more difficult if you want Police 468 MHz RX only and UHF CB, and becomes a challenge if you want to add 490 MHz or low 460 MHz frequencies into the mix, too. Normally, you will be able to get about 40 MHz bandwidth for receive, and 35 MHz bandwidth for transmit, but this will take some very fine adjusting and fiddling to achieve this result. When used in the RF board's 'native' band (i.e. a U band board, unmodified and programmed as a U band, I managed to get 425 to 475 MHz RX, 435 to 475 MHz TX) you can expect nearly 50 MHz receive coverage, and 40 MHz transmit, using software 'out of band' mods only. These figures, of course, relate to UHF versions.
One interesting variant is the genuine UW band unit. These can cover from 443 to 520 MHz for both TX & RX with only appropriate software programming. The sensitivity is only about 1.5dB behind the other UHF versions, but maintains this sensitivity level pretty much across the band, drooping only another 3 dB towards the band edges. The genuine UW band units appear to achieve their phenomenal bandwidth capabilities by using not one, but two varicap diodes across each VCO resonator, and this is probably coupled with appropriate software control of the 'VCO pulling' voltage fed to those varicaps. There are other changes as well, to help the VCO cover the wider bandwidth, but the main changes seem to be the extra varicap diodes. Programming a genuine UW band unit as a W4 is pretty much a waste of time: TX coverage is limited to, strangely enough, a 10 MHz area around 510 MHz, but RX is a bit better at 494 to 530 MHz. Programming a genuine UW band unit as a U band unit produces some interesting results: TX and RX from 435 to 483 MHz, meaning that this is the only PRM80 variant (with appropriate software modifications) that can cover both the amateur 70cm band, if only partly, and UHF CB, obviously with reduced sensitivity at these band extremes, about 6dB behind the normal figures. Programming a genuine UW band unit as a TU band produces 430 to 480 MHz - similar results to the U band only as above. 20 or so MHz coverage is more normal for VHF versions.
This W4 to W1 or UW band conversion can also be followed in principle (i.e. adding trimcaps to the resonators) to lower the frequency coverage of any of the UHF units.
The trimcaps can be replaced using fixed value disc ceramic capacitors or even surface mount capacitors, see notes below about using these mods in a PRM80 destined for mobile use.
Is the W4 to UHF CB conversion any good? Is it as bad or as good as some people say?
The method of swapping RF boards and modding W4 boards to cover W1 frequencies works, and works very well. Here are a few unabridged, verbatim quotes from some happy modified PRM8030 users: "Just thought I'd drop a line to say that the radio has been working beautifully since you modded it. An A9 fitted with a W4 board that does W1 frequencies as well as an original W1 8030. I borrowed a W1 off a friend for a few days and challenged a few friends on radio to tell me on air which one was which - they couldn't pick one from the other !! I was telling an amateur friend of mine about it and he put it on his test bench and told me that all your quoted figures re: Tx power, sensitivity, etc were spot on."
and another: "Just got back from holidays, so this is my first chance to thank you for a terrific job you have done on the radios I am very very pleased they work really well TERRIFIC."
and another: "Works like a charm! Thanks again!"
and another: "And last but not least the performance on narrowband (12.5) is amasing. The scary part is how good the rx is on a 25 k signal, loud and clear"
yet another: "working very well indeed... "
and another: (they are) "Working fine"
Several people over the last six months or so have been making comments to the effect that these modifications are 'butchery', 'perform poorly', 'have reduced power output', 'poor sensitivity', 'poor reliability', 'sound bad', 'heat up too much', 'draw too much current' etc etc and that 'genuine W1s are the ONLY way to go', 'W4 modification doesn't work' or words to that effect.
I can only presume that these people are basing their judgement on poorly modified or tuned radios, or want to generate some prestige in owning a genuine W1 band unit. I have modified some 200 W4 radios to work on W1 band, and not once has anyone complained of the above problems, and as you can tell from the above quotes from happy owners, they certainly think highly of their modified units. I personally test the power output, spectral purity and sensitivity of each and every unit I modify and have yet to see a UHF (12.5k version) W4 to W1 conversion achieve worse than -12 dBuV (about 0.25 uV) for 12dB SINAD, or less than 25 watts RF power output (and yes, this is measured with current in-calibration equipment). Indeed, my modified W4 units are slightly more sensitive than my genuine UW band unit! You know what? My UW unit stays in it's box and never sees any use, and the modified W4s are in use all the time, and I prefer to use the modified W4s over the UW unit. I think that puts to rest the argument that they are poor performers / poor output power / poor in the sensitivity department.
My own modified 8030 units have been with me for three years now, and are in daily use, and have not suffered any problems mentioned above, so that should answer the reliability issue.
I decided to put my UW band unit to the test against a well modified W4 band unit, using the same head, the same microphone, the same dummy load, same power supply, and same environment. At 25 watts, the UW drew 6.50 amps, and the modified W4 drew 6.65 amps - an extra 150mA. Big deal!
A 10 minute continuous transmit test showed something interesting: after the 10 minutes, the UW band unit had dropped to 23 watts, and had a heatsink temperature of 45.0 degrees. The W4 after 10 minutes was still transmitting at 24.7 watts, and had a heatsink temperature of 47.1 degrees. An extra 2.1 degrees, probably the result of maintaining its power output close to 25 watts. I just can't see why an extra 2.1 degrees is considered 'heating up too much', or why 150mA is considered 'drawing too much current'. Note that the PRM80s are not designed for this sort of high duty cycle transmissions, so if you do wish to talk for extended periods, try if possible to use low power settings.
PRM80s modified sounding bad? Well, as one user above has claimed, he had a genuine W1 and a modified W4 side by side and challenged on-air listeners to pick the difference. They couldn't. One thing that may be causing this impression is that the PRM80 controller microphones have a common fault which develops over time, causing a soft crackly sound to be transmitted, and this fault can be easily fixed; see below. Also, the PRM80 series don't have that nice Hi-Fi sound of the Sawtron or Kenwood radios, they do filter the audio fairly tightly, especially the 12.5 kHz variants - after all, it is a workhorse, not a show pony.
Here's an interesting quote from a PRM80 owner who has both a genuine W1 and a modified W4: "oh, by the way I am now the proud owner of a GENUINE W1 PRM 8030. Not that it matters, I still find both radio's work equally well. "
I do agree that genuine UW radios do cover large bandwidths much better than W4s or W1s tricked into being UWs, but this shouldn't be a concern to most people who only want to cover UHF CB and Police UHF RX only. The modified W4s do this function exceedingly well.
Be assured that there are at least 200 of my modified PRM8030s in Australia that are living proof that the W4 to W1 modification works, and works very well indeed.
I came across one 'W4 to W1' conversion that had been poorly done; there had been way, WAY too much solder used, and the soldering iron used was obviously too big as it had burnt surrounding components. The capacitors used were not in especially good condition, and overall the modification had been poorly executed. Not suprisingly, the radio did not work very well at all. In fact, the excess solder had flowed inside the resonators and had ruined them. Like anything, if the job is well done, it will give good results. Poor work equates to poor results. The point I am getting at here is that the information I have provided here is good, but I don't have control over the quality of the work that others do when using this information, so don't go blaming me if things go pear shaped. If you have any doubts as to the quality of your soldering, or your ability to understand and properly use this information, then stop, and get someone else to help you, lest you ruin your radio.
Improving sensitivity in a genuine W1 band radio:
This section would be equally applicable to any of the UHF versions of the PRM80 series to very slightly improve the sensitivity within the band that the radio was originally designed to work in. For example, a narrow band (12.5k) genuine W1 radio needed 0.239uV to give 20dB quieting. With the addition of trimcaps to each RX front end resonator and then very carefully retuned paying particular attention to the tracking gain adjustments, this figure drops to 0.211uV (about 1.1 dB improvement). If you can, getting a trimcap with a low end adjustment of less than 2pF would be best, for example the RS Components 832-295 1.4 to 3.0pF surface mount trimmer. This works because the tracking voltage fed to the varicaps across each front end resonator is not perfectly matched to each radio - it is only a close value for the typical radio. What you are doing here is to add an individual capacitance to each individual resonator plus the varicaps own tracking adjustment - it is like fine tuning each resonator for maximum performance. This also explains why the W4 to W1 modification with trimcaps often produces a radio equally as sensitive, if not more so, as a genuine W1.
The single band into UW dual band conversion:
Well, here's an interesting one. Just changing the hardware code alone from a single band RF board to a dual band RF board (i.e. W1 into a UW) sometimes doesn't work. The divider ratios change, and the VCO simply does not always lock properly. However, I have personally changed many a W4 band only dual mode, 12.5 kHz radio into a UW band unit that does quite happily span from at least 460 to 490 MHz. The W4 RF board was modded in much the same way as described above: capacitors added to the resonators and careful adjustment of the VCO and tracking gain adjustments, and programmed as a UW band, dual mode, 25 kHz unit. Note the change from 12.5 kHz to 25 kHz.
Yet another W4 unit, a single mode type this time, did not modify well to UW configuration - it had to be changed to a W1 band only unit because the VCO refused to lock while in UW configuration. I do not know why this happened, it might have something to do with the way the dual mode firmware handles the control voltage for the VCOs? Still another W4 band single mode unit could not be programmed as a UW band at all (the FPP software rejected the hardware code change as being not compatible) but could be reprogrammed as a W1 only. You will just have to try it and see.
I have not tried this modification using a W1 or U band only RF board to turn it into a 'wideband' UW unit, but a similar effect can be achieved by programming out of band frequencies into the unit using a method described below, with quite acceptable results as detailed above (see the comments about using a RF board in it's 'native' band with out-of-band software mods only).
The VHF to UHF (or vice-versa) conversion:
So, you have bought yourself an E band (68-88 MHz) radio reasonably cheaply and want to turn it into a UHF CB. Change the hardware code, and program UHF CB channels into the thing will work OK, won't it? You certainly will be able to fool the VHF radio into thinking it is now a UHF radio, but believe me, it just wont work! You can't turn a front wheel drive car into a rear wheel drive car by turning the seats around to face the opposite direction any more than you can change a VHF radio into a UHF radio just by changing the hardware code alone! What you will need to do is to remove the VHF RF board and replace it with a UHF RF board. Or you replace the RF board with any band RF board as you desire. Where do you get RF boards in the band that you desire? You can try any number of places - a local amateur radio operator, a local radio service technician, even another radio enthusiast that may have a spare RF board in the band you want as a result of reading this information! Unfortunately Rockby Electronics have now sold out of their W4 band RF boards as of 13/3/2001. Another source might be Keycom, where W4 band boards cost $50, and genuine W1 boards used to cost $120 (they are all sold out of W1 and A/B band boards now) which doesn't include postage. (there's the supply-and-demand theory at work again). Be patient for a reply from Keycom - he only checks his mail on Thursday nights, so I'm told.
Even I have run out of RF boards, and I don't know where you can get any more, other than Keycom (see website mentioned towards the end of this document)
If you find that all this tuning is a bit beyond you, I can help out there. If you are the trusting type, you can send your unit to me and I will tune / modify / set the radio up and return it to you. First read the prm80qs.txt file then email me at mitaux8030@hotmail.com for more information.
These instructions are applicable for any RF board change overs, be it from VHF to UHF, or VHF E band to VHF B or A band, or any other combination thereof.
1) Power up the radio, connect your interface cable, and read the present configuration
2) Save the configuration, so if things go wrong, you can revert to the original, and most
important, switch off the power, and remove the power plug.
3) Using a torx T8 driver, undo any retaining screws on the RF shield cover and remove (if present)
4) Unclip the control board to RF board ribbon cable, by pulling up on the edges of the retaining collar of the plastic connector. This should allow the ribbon cable to come free from the connector very easily.
5) Desolder the antenna connection and the power feed through from the RF board.
6) Using a torx driver, unscrew the screws holding the RF board to the chassis. Also undo the screws holding the RF power device(s) to the chassis, and any other transistors or devices that may be held down by screws.
7) Gently remove the RF board, and put it aside in a safe place. Who knows, another radio enthusiast might want to buy that RF board from you! Try to find an anti-static bag to store it in...
8) Get your new board, and lay it in place onto your chassis, and look at the screw holes; see if there are any 'new' screw holes that do not have a thread. If changing from a VHF board to a UHF board, you will find that the VHF chassis has the holes pre-drilled but may not be pre-tapped for the UHF driver & pre-driver transistors or the power control transistor. If you find that you do need to tap new threads, you will need to remove the control PCB from the other side of the chassis, so that any swarf produced by cutting a new thread doesn't fall through the hole and end up under the control PCB and cause a short circuit!
9) Once you have cut any new threads (if applicable) wipe clean any heatsink compound goop off the chassis and the RF devices on your new board. A bit of metho helps here. You may as well give the rest of the chassis a quick wipe over, too, just to make sure no metal chips or swarf etc remains. Apply a thin but even coating of new heatsink compound goop to the RF power devices and their mating areas on the chassis.
10) Gently position your new RF board into place, and replace any screws for the RF power devices, UHF power control transistor (looks like a black plastic encapsulated TO220 device) if applicable, and the two screws near the RX resonator filters (these are indicated by a small arrow on the PCB) and gently tighten. Then tighten further, but not too tight (the screws break or threads strip quite easy). Make sure that the metal clip that acts as a PCB spacer and heatsink for the small pre-driver transistor on the underside of the RF board is in place - it is easy enough to lose. If you do lose it, do not use a screw in that hole - you will end up bending the PCB!
11) Solder the antenna connector & the power feed through, re-insert the ribbon cable and lock in place the retaining collar
12) Now reprogram the hardware code to suit your new RF board (or to suit modifications to the RF board); you will have to temporarily reconnect power to do this.
13) Perform any modifications as you desire to the RF board, and tune (don't forget those extra screws to temporarily hold the board down as you tune it)
14) Once again remove the power to the radio, replace the RF shield, and tighten the screws for this firmly, but not too tight. No RF shield? Better get one - they do make a difference, especially if you are asking your radio to span a reasonable bandwidth or are using the unit in a mobile or RF hostile environment, and unstable TX can result. Also note that if the shield came from a VHF unit, not all adjustment holes will be present for UHF adjustments and vice versa. Best to make as many adjustments & tuning before the RF shield is replaced for good. One point to note is to always adjust the frequency fine tune after the shield has been replaced.
Be careful using the T8 Torx tool - the tip of them can be mangled easily if you are too rough or tighten them too far. Also don't try to use a screwdriver in place of the correct T8 tool - this will not only damage the Torx screws, but you will not be able to achieve the correct torque on the screws necessary to hold down the RF shield. They need to be tight for good RF shielding properties, but not so tight that they make a 'snap' noise when being undone. In short: get the right tool and use it carefully!
I also found one problem with swapping RF boards. There was a UHF 8010 that I wanted to convert to a VHF one. After swapping the appropriate VHF board into the 8010 I found that it did not work - no RX or TX, and the Local Oscillator was only 'locked' at some weird frequency every third channel or so. Yet the same RF board worked perfectly in another 8020 and 8030. What gives? I noticed that the 8010 was a fairly early version (build date in 1989) and the original UHF board was also 1989 build. I managed to find an early build VHF board (also 1989), married that with the 8010, and things started to work. If you have similar problems, you might try using an early build PRM80 RF board. The problem apparently lies in the divider outputs - one output can sometimes be slightly low in level, and while some boards are tolerant of this, those that are not cause the PLL not to lock or to lock at wierd frequencies. Replacing the divider will fix this if you don't have access to other RF boards to fix by mixing 'n matching. The divider can be found on the RF board, the IC is a SP8718 in all bands and versions, and it is designated IC402.
Programming out-of-band frequencies into your PRM8025/8030.
You may have noticed that you can't program frequencies outside of the designated band of the radio. For example, if you have a W1 band only radio, and program it for UHF CB, the FPP software doesn't allow you to program in 468 MHz frequencies for police RX only. There is a way around it, and it uses a bug in the standard FPP software. Here's how to do it, with two specific examples of adding 468 MHz frequencies into a W1 (or modded W4 programmed as a W1) band unit:
1) Create your profile with all the features etc that you want, less any out of band frequencies, and program that into your radio, and test thoroughly.
2) Once you are happy with your configuration, less the out of band frequencies, re-read the configuration into the PC and save the configuration. Take note of your present hardware code and write it down.
3) Disconnect the programming interface from the radio
4) Have the configuration open, and edit the hardware code to be a VHF A9 band unit, of similar hardware configuration to what your unit really is now. To do this, when in FPP, press 'escape' to bring up an overall menu tree. Then press 'F2' and a new menu will come up. Now scroll down to 'Change Hardware Code'. You will then be taken back to the overall menu tree. Scroll to 'A - Hardware Configuration' and you will then be able to re-select your hardware code (ie change the hardware code of this existing job). If your original unit had a hardware code of 9525 001 10845 (a 8030 remote W1 25kHz unit), you would change the hardware code to 9525 001 10840 (a 8030 remote A9 25kHz unit)
5) Go back to editing frequencies. You will notice that your frequencies have changed into VHF frequencies. That is fine - if you look closer, you will see that the VHF frequencies actually relate to your original UHF frequencies (the divider ratio is the same) e.g. 476.425 MHz in W1 band becomes 155.71250 MHz in A9 band.
6) Now the tricky bit: extrapolate the out of band UHF frequencies to VHF frequencies. Hint for W1 band units: 467.850 MHz becomes 151.4250 MHz, 467.875 MHz becomes 151.43750 MHz and so on until 469.425 MHz becomes 152.21250 MHz. The document
called UtoV.doc will help you with this, or you can use the excel file uhf-VHFcalc.xls to calculate other out-of-band freqs to enter.
7) Once you have finished entering all your 'VHF' frequencies, press 'ESC' then 'F2' then scroll to 'Change Hardware Code' to get back to the menu to change your hardware code. Change the hardware code back to your original one, and then view the frequency table. You should verify that everything is as you want it before saving the file, and writing it to the radio. If you do need to make changes or correct a mistake, you will need to change the hardware code back to A9 band, and edit in that configuration.
8) Don't forget that if you enter out of band frequencies, you may need to retune (and modify in the case of UHF versions) the RX VCO to cover these frequencies. Of course, if you enter wildly out of band frequencies, the VCO will probably not cope at all!
Based on this method, you could program (note: not operate) the following ranges:
W1 band normally 470-500 MHz, can become 457.000 MHz to 513.000 MHz
U band normally 440-470 MHz, can become 427.000 MHz to 483.000 MHz
W4 band normally 494-520 MHz can become 482.000 MHz to 538.000 MHz
UW band normally 450-520 MHz can become 443.000 MHz to 520.000 MHz
TM band normally 400-440 MHz can become 392.000 MHz to 448.000 MHz
E band normally 68-88 MHz can become 64.000 MHz to 92.000 MHz
B band normally 132-156 MHz can become 130.000 MHz to 158.000 MHz
A9 band normally 146-174 MHz can become 141.500 MHz to 180.000 MHz
(to expand the A9 band unit, change to TU band to get down to 141.500 MHz, and change to UW band to get up to 180 MHz)
However, take note of the practical operating bandwidths as noted earlier. This procedure is most useful on the VHF and 'modded' W4 versions, since you can, within reason, shift the VCO coverage to suit your requirements.
Programming slightly out of band frequencies on UHF versions of the 8020 and 8010 is suprisingly simple - the software just takes the frequencies as you type! For example, the W1 versions will allow direct frequency inputs down to 467.000 MHz without any trickery, but the VHF versions will not allow any out of band frequencies at all. I have yet to find a simple way to allow either VHF out of band frequency entry or 'very out of band' frequency entry on the UHF versions. By the way, the software also allows high power on UHF CB without any problems, either.
Recently, cracked versions of FPP have become available that allows 'out of band' freqencies to be entered directly without the above hardware code swapping - but there is a drawback. The cracked version of the 8030 FPP is an early version (v2.1) that only supports PMR 8030 remotes - no dual mode, no 8025, no PRP80, no nice extra features that the later versions of FPP enables. And even so, the software does not allow 'out of band' frequency entry to be any further 'out of band' than the above hardware code swapping method will allow. Still, some people may find it useful.
The cracked version of the 8010 & 8020 software is version 3.01 (quite recent) and does indeed allow very out-of-band frequencies to be entered - even as silly as 40 to 188 MHz for E band units, though other bands are a little more sane at 130 to 170 MHz for A band, or 450 to 500 MHz for W1 band, for example. Mind you, some pretty serious work would have to be done to the VCOs, synthesiser, RX and TX chains, that assuming the synthesiser has the ability to divide to such limits in the first place.
Programming high power for UHF CB frequencies.
Note: doing this is very naughty! It is, in fact, illegal. But, it is presented to you here for 'educational' purposes only. Besides, given that the procedure is similar to programming out of band frequencies as above, it probably wouldn't have taken you too long to have discovered this trick anyway. Lets press on.
Just like the process for programming out of band frequencies listed above, you can read the configuration from your radio, disconnect the programming interface, then using FPP change the hardware code to a similar one but in a VHF A9 band unit that has 25 watts as standard, and then edit the channels for high power, leaving the frequencies and everything else alone. Then change the hardware code back to your original code, and you will see that your UHF CB frequencies are now available with high power. Do not edit anything in the channel list after this point. Save your high power configuration to disk, and then write it to the radio. Don't forget that high power TX is more demanding of your power supply and of TX VCO filter tuning of the radio, so be sure that both these areas are spot-on and fully tested & stable first, especially if you have only been operating your radio at 5 watts beforehand.
When adjusting the power output of the radio, R581 sets the 'high' power setting, normally 25 Watts, and R578 sets the 'low' power setting. Make & check any adjustments twice because there is some interaction between R581 & R578. Do not adjust the radio for more than 25 Watts output - the unit will last longer if you do. If you tend to waffle a lot, then I'd suggest that you back the output power down to 15 Watts. Of course, if you wish to remain legal, then there is nothing to stop you from setting 'high' power at 5 Watts, and 'low' power to 1 or less watts, and your radio will be able to transmit at these power levels nearly continuously without being stressed at all. It is amazing how far even 100mW will travel given a good antenna & coax. Note that the transmit arrow will cease to light up below about 500mW, but the radio is actually still transmitting, if you decide to set the power that low. If you wish to program high power for UHF CB on the 8010 or 8020, just enter the power setting to "H" - that's it. The program doesn't complain at all, strangely enough!
Programming in 12.5 kHz step channels on a 25 kHz radio:
No matter what the band, just enter the 12.5 kHz step frequency as you desire. It will work! Note that this does not magically narrow your receive filter to suit 12.5 kHz channels, nor will it decrease the deviation to suit 12.5 kHz channels. To be transmitting on such channels, you will need to reduce the deviation to suit the narrower bandwidths involved. For receive, either you can put up with reduced adjacent channel rejection, or replace the filters to suit. And you really should get a higher stability reference oscillator, too. This is not an easy job!
Conversely, if you get your hands on a radio unit that is intended for operation on 12.5 kHz channels and want to use it on 25 kHz channels, you will need to increase the deviation so that you don't sound so quiet to everyone else. Strangely, the 12.5 kHz narrow filters don't seem to 'clip' the wider 25 kHz channels on receive, but if you come across a signal that is not dead-centre on frequency, that signal will sound scratchy (common on UHF CB where the operator has blindly adjusted every adjustment including the frequency 'netting' in an attempt to get more RF power/deviation/everything else). And having the higher stability reference oscillator doesn't hurt one little bit. There are other differences, but these are so minor that you shouldn't be concerned about them when using a 12.5 kHz unit on 25 kHz channels.
There are other mods that you can do that have nothing to do with the radio side of things. You can modify the display backlight colour by either changing the light bulbs within (the pretty coloured 1.5volt grain of wheat bulbs from DSE Cat. P8120-P8124 are good, but make sure to use a current limiting resistor - I suggest at least a 68 ohm resistor for the two bulbs in series when powered directly from the backlight switching transistor supply, otherwise you risk burning the bulbs out prematurely) or by removing the existing bulbs and applying a thin coat of paint of your own choice. Green looks nice, as does blue.
There is a much better modification for the display backlight colour detailed at the PRM80-series yahoogroups, this uses 3mm blue LEDs. Take a look at:
http://groups.yahoo.com/group/PRM80-Series/files/Backlight%20Modification/
http://users.bigpond.net.au/fragfest/8030.jpg gives you an idea of orange backlighting.
You can also alter the LED backlights of a keypad microphone - just observe the polarity carefully - the PCB indications are not correct. The use of diffused, standard output (i.e. not the super bright, narrow beam types) LEDs work best. I chose to keep the standard green, but blue LEDs look good, too, and I imagine yellow or orange would be quite OK, too.
I also found that the minimum volume from the speaker was too high for a quiet environment. There are two methods around this - one is to place an attenuating pad before the audio amp inside the radio, but my preferred method is to use a pad in line with the speaker itself. That way, you can quickly remove the pad (which can be as simple as a 27 ohm 5 watt resistor in the hot audio line) if you need to. Or you can simply use a smaller, less efficient speaker, but these don't sound as nice. By the way, I also replace the audio connector to a standard 3.5mm audio socket & plug, which makes it easy to change & compare speakers.
If you are removing the mike cover constantly to experiment with reprogramming the unit, you might want to use a pair of sharp diagonal cutters to remove the tab that locks the mike cover in place. This makes the removal of the cover easy using just firm finger pressure rather than having to resort to a small screwdriver all the time, and the cover will still remain firmly in place during normal use. Some people have asked how the microphone cover is removed so access can be gained to the microphone connector (and hence remove it for programming). At the very top of the microphone connector plastic cover, near where the 'Philips' or 'Simoco' is printed, insert a small screwdriver into the gap and gently and slightly lever the top of the cover outwards towards you, then using the screwdriver lever the cover downwards. The plastic cover should start to slide down. From here, you can use your finger to slide the cover down about 5-8 mm and then the cover will lift off. Once the cover is removed, you will find the microphone connector is being retained by a little tab, which needs to be pushed down to allow the connector to come out (just like a telephone modular connector, and like the RJ45 connector in use for the PRM8030 remote cable, or RJ45 connector you might see in a computer LAN). When removing the microphone cover, it is easy to break it, so be gentle, and you can use a little piece of cloth over the screwdriver to help prevent the screwdriver from marking the plastic. Also, when pushing down on the tab for the microphone connector, make sure power is off to the radio - this will prevent damage to the radio if your screwdriver should slip and go deep inside the connector, possibly shorting something out.
The volume knob of the PRM80s has no pointer on it for you to see roughly where the volume is set to - which is of course very easily rectified by a dot of paint, a small sticker, or removing the knob and cutting a fine notch in it with a fine file or hacksaw.
Custom creating a label for your definable buttons is easy - just fiddle around with your choice of word processor to create a label, print it out, and fit it under the clear plastic bezel. You will need to fiddle heaps to get the spacing right, but the end result looks great, and is very practical indeed. A laser printer produces the best results.
If you like to waffle a lot, you will find that the heatsink will warm up considerably even on low power. This can be remedied by using a small 12 volt CPU fan fitted to the heatsink. Use a pair if you are really worried. I've not done this to my unit, and so have not explored how to affix the fans to the heatsink. Maybe a custom made bracket could be made up, or some other cowling or the like could be fashioned fairly easily.
There are rumors that the 64 channel PRM8020s can be programmed with more than 64 channels. This possibly comes from the fact that the PRM8030 normally can only have 100 channels, but with the V4 'Xtra' version of FPP you can use up to 160 channels - apparently achieved by sacrificing memory used for holding voting channels for 'normal' channels. Well, the definitive answer is that the 8020 can not have any more than 64 channels. Sorry.
More than 10 channels for the PRM 8010?
I've not tried this, but others have and they say that this works well. If you have a later model PRM8010 with a version 2 control board, you can replace the head/display with a PRM8020 type (or a discarded 8020T display which are identical), then reprogram the hardware as a PRM8020 and effectively turn the radio into a 8020, then reprogram the software side of things, complete with 64 channels. To check if you have a version 2 control board, look for the very small surface mount 16 pin IC203 near the centre of the control board, the EEPROM that stores the channels. If this IC is a NMC93C566, often marked just 93C66 (8kbit memory) then you are in luck, this modification is possible. If the IC is a NMC93C556, often marked 93C56 (2kbit memory) then you are out of luck. It would appear that radios produced after the early 1990s had the 8k chip in them. Another way of checking is to use the prm80HW software to tell the radio it is now an 8020, and if the radio display lights up with channel '1' then everything is OK, but if random segments are lit, then you can not do the conversion.
Also, before anyone asks, converting an 8010 or 8020 to become an 8030 or 8040 is not really feasible. It would be much easier & cheaper to find a second hand 8030 or 8040 in the first place.
The combined speaker / power connector
If you have a radio that has no power cable, you will note there is a four pole connector on the back where the heatsink is that is the combined power and speaker connector. If you look at the radio from the rear, with the BNC antenna connector on the left, the four pole connector on the right, the pinouts for this connector are, from left to right:
1 (pin closest the centre-line of the radio) : DC power positive ( + ) 13.8 VDC
2 : DC power negative ( - )
3 : speaker connection +
4 (pin closest the edge of the radio) : speaker connection -
Note that the radio should only be installed in 13.8 Volt DC negative earth vehicles. For use in positive earth vehicles you need to isolate the entire radio & antenna, including things like antenna mounting brackets, microphone & radio brackets from the vehicle chassis. For use in 24 volt vehicles (aircraft, trucks etc) then you need to use a voltage reducer rated at 8 amp continuos.
Programming a 8010 or 8020 from scratch (especially if you have swapped RF boards) is not an easy task - to change the hardware code, you need to use the PRM80HW software to do this. Unfortunately, this software does not give a nice list of valid hardware codes to select from like the 8030 software does. You can specify your options and the software then tells you the hardware code applicable to this; more often than not this results in an 'unknown or invalid hardware' error. The other option is to directly type in the 12NC hardware code - it turns out this is easier. The following is a list of hardware codes available - just try them until you get a code that matches your configuration the closest; type in 9525 001 and then the last five digits:
PRM8010:
10000 to 10013, 10024 to 10037, 10048, 10050, 10192 to 10205, 10242 to 10255, 10292 to 10305, 10342 to 10355, 10394 to 10407, 10422 to 10435, 10472 to 10485, 10496 to 10509 and 10522 to 10535.
PRM8020:
10216 to 10229, 10316 to 10329 and 10366 to 10379.
You will find that the codes follow a repetitive pattern, making the task of choosing a hardware code a little easier. Also, you don't need to worry about the hardware code telling you weather or not your unit might or might not have a noise blanker, or a standard speaker or a standard mounting bracket etc. Just so long as you get the frequency band, the selcall option, the CTCSS option and the bandwidth bits right, choose any code that fits best.
Aligning the mute for the PRM80 series:
This adjustment can be very critical: get it wrong, and your mute won't open until a signal is largely noise free. Get it right, and the mute will open on very weak signals indeed, although your results will vary slightly from unit to unit.
Firstly, set your mute to level 02 - this is very important. Then adjust R455 anti-clockwise until the mute opens, and white noise is heard. Then, VERY slowly, turn R455 clockwise until the mute closes again, and stop there. If you regularly operate your radio in extremes of temperature (in a car, for example), then you will find that you will either have to occasionally operate your mute at 04 level or even higher to mute reliably, or in the above tuning process, advance R455 only slightly past the point where the mute closes, and sacrifice some mute sensitivity. The reason for this is the mute noise amp is slightly temperature dependant - heat seems to cause the mute to become reluctant to close.
Setting the mute using these instructions produces a very sensitive mute, and may not be suitable for operation in a high noise floor environment such as in Sydney or Melbourne. If you find this is the case, you will need to set the mute at 04 or 06 or even more in FPP as your default setting. That way you can still have a very sensitive mute if you need it, but under normal operation, the mute should behave itself.
Improving transmitted audio on the PRM80 series:
When I had a FM91, I found that the standard microphone sounded OK with everyone else's voice on transmit, except mine. For whatever reason, my voice took on a gravelly, harsh quality. The fix was deceptively simple - replace the standard dynamic microphone insert with an electret condenser type. I found a similar thing happened on some PRM80 units, and the fix again was the same. Replacing the standard dynamic microphone insert with an electret condenser type is easy, just make sure that you bias the positive side of the electret condenser insert via a 100 kohm trimpot from the +8 volt supply that you will find inside the microphone preamp board, and pass the same positive connection from the electret insert via a 0.01 to 3.3uF tantalum capacitor to the 'hot' side of the microphone preamp input. Your choice of capacitor that you use will depend on how much 'bass' you want for your transmitted audio - the higher the value, the more emphasis on bass there will be. This will also be dependant on the electret insert itself. Experiment with this value to reach the best quality for your voice. If you find the standard microphone works well for you, then there is no need to, nor recommended to do this. I have also found the standard microphone (i.e. non-controller, non-DTMF) sounds better, too, so try this if you do not need the extra functions offered by microphones with a keypad. You will never get a 'hi-fi' sound like that of the Sawtron range of radios with the PRMs - they filter the transmitted audio very heavily indeed - 300 or 500 Hz (depending on CTCSS installation) to 2550 Hz for the 12.5 kHz radios, or 3000 Hz for the 25 kHz versions. Compare this with 100 Hz to 5000 Hz for a typical UHF CB without CTCSS. To fix this problem, you can add a 0.1uF capacitor 'across' the TX audio low pass filter on the RF board. While this will not increase the low end response below 300 / 500 Hz since that part of the filtering is done in the CTCSS IC (FX365LG on the control board), it does increase the top end of the audio to about 5500 Hz. Add this 0.1uF capacitor between the 'cold' side of R560 and the 'hot' side of R569. R560 (12k ohms for most units, except the 12.5kHz UHF variants which use 15k ohms) is right at the very front of the RF board very close to the flexi-track connector - it leads to pin 1 of that connector. The 'cold' side of this resistor is the side furthest away from the flexi-track connector. R569 is the resistor that takes the audio to the TX VCO circuitry - its track can clearly be seen running towards the TX VCO area. This resistor is a 0 ohm jumper on all UHF units, and is 220k ohms on A band units or 68k ohms on E band units. The 'hot' side of this resistor is away from the VCO circuitry. A word of warning: soldering this component is not easy, due to the proximity of the plastic flexi-track connector near R560 and the shield adjustment 'hole' that comes down almost on top of the nearby variable resistor leaving very little clearance. Like many other mods this page details, you will need a fine soldering iron tip and very good soldering skills.
There is a fault with the 'controller' mikes direct out of the factory that causes a 'soft scratchy' sound on TX - see the "Common Faults" section on how to rectify this.
Another problem that is noticed is an audible 'tick' on transmit every two seconds for the remote head models. This is caused by the data lines on the remote cable 'crosstalking' into the audio line. A solution is to keep the remote cable as short as possible, which of course implies a custom made cable. Another solution for those who can't avoid long cable runs is to replace the audio line of the remote cable with a shielded one. The diagram below will show you which conductor to shield. Again, a custom made cable is required. These two solutions don't entirely eliminate the problem, but can make the 'tick' almost imperceptible.
Based on the diagram above:
Pin 1: Transmit (microphone) audio from head to transceiver body
2: Ground
3: Low level speaker output
4: +9 Volts DC
5: Mic ground (same as pin 2)
6: On/off control
7: RX data into transceiver from head
8: TX data from transceiver to head
Please follow the pinouts above, on which I have based my table above. I have searched high & low, and not found a definitive pinout for the RJ45 connector. For every diagram I found, I found another that was the opposite. Whoever is right or wrong, I have based my findings on the diagram above. Note that these pinouts are for the remote interface cable going between head & body of the radio, NOT the microphone connector.
To reduce the 'tick' induced into the transmit audio, shield the wire that connects to 'pin 1' with the shield connected to 'pin 2'. Only shield the microphone audio wire by itself. Do not have two earth paths via pin 2 (possibly creating an earth loop). You could try using pin 5 as the shield earth instead of pin 2 if you find pin 2 does not produce satisfactory results.
Another possibility is to use a 'straight thru' RJ45 twisted pair LAN patch cable WITHOUT any crossovers. Unless you know for sure there are no crossovers, do not use this sort of cable, as damage to your 8030 will result. This will not be quite as effective as the above methods, but does give some improvement at least.
Programming the PRM80 series
Please note that this section is for complete new commers to the two way radio scene. Radios such as the PRM80 are primarily designed for business users who have their own privately licenced frequencies, each with unique needs. Radios for this purpose are built to cover the needs of a wide cross section of users, and to customise the radio and enter the required frequencies suited for a particular user, the radio must be programmed with a computer and interface that connects the radio to the computer. How is this done? Briefly, the computer runs software specific to the PRM80 called "FPP" or Field Personality Programmer. PRM8010s and 8020s use one version of FPP (called PRM80hw.exe & PRM80sw.exe), PRM8025s and 8030s use another (called 8030xxx.exe where xxx is the version number), and PRM8040s use yet another version (called RPM8040.exe). The computer then communicates to the radio via an interface (details below) that loads the required information into the radio. This only generally needs to be done the once for each radio, though if a change is required (say a new frequency needs to be added) then it is only a short process to re-load the new 'personality' into the radio with the computer.
Some people think that the process of programming radios by computer is akin to magic - that it can turn a VHF radio into a UHF one, or make a 8010 into an 8030. This is simply not possible. The computer only personalises the radio consistent with the hardware that the radio has been given at manufacture (or the modifications you perform to it).
When programming the PRM80 series, the programming interface plugs into the serial port of the computer COM1, and the other end plugs into the microphone socket of the radio. If the radio has been fitted with a modem card, then a simplified programming interface can be used between the computer serial port and the DB15 connector on the rear of the radio.
Learning to use FPP is an aquired task, and while entering frequencies is reasonably straight forward, learning all the inter-dependant options & features takes some time & thought.
When programming your radio, it is best to plug in the interface (either microphone socket or DB15 connection) with the radio off, then turn the radio on, program the radio, turn off the radio then remove the programming interface. This is to prevent possible damage to the radio.
The dreaded "beep-boop" EEPROM corrupt problem
A word of warning here: constantly reprogramming your radio is not a good idea. Apparently there is a finite limit to the number of times a radio can be programmed and while it should number into the hundreds of times, one unit I was playing around with was working fine and I wanted to make one small, final programming adjustment. Once that was done, the radio stopped working (no display, no TX or RX), emitting a constant beep-boop, and it wasn't due to mis-programming in any way. It appeared that during the reprogramming sequence, there was an EEPROM corruption - constantly changing your programming will only increase your risk of disaster such as this eventually striking.
This is normally a fatal problem which can be recovered by using special software which I can not 'give out' - you will need to email me if this has happened to you. So be warned! The more you reprogram the radio, the more you run the risk of something happening that corrupts the EEPROM.
However, two hints that have turned up are to:
1) try to program the unit with standard FPP, and while the software is writing, remove the programming lead half way through the process. Then use FPP to write once again. I have tried this method and sad to say it did not work for me, but if this has happened to you, then you have nothing to loose by trying it anyway.
2) remove power from the radio, discharge the memory backup capacitor (C283, a black surface mount capacitor located between the 0.5 Farad 'supercap' and the RAM IC) for 10 seconds, and then short out all legs together of the EEPROM IC, then reprogram the unit with the standard FPP. The EEPROM is IC219b, a X24C16 on the underside of the systems & control board, near the side edge on the same side as the remote interface connector (microphone connector on 8025s). I have not tried this method, but have been told it works.
If you can not recover from the problem, then there is a high probability that the special 'EEPROM formatting' software will work - I have had 100% success so far - you will need to e-mail me about this.
Sometimes, especially when doing a local to remote or vice versa conversion or 8030 to 8040 conversion, this 'beep-boop' problem will appear - a reprogram with FPP with appropriate settings should fix this.
This is a very commonly asked question, so I thought that it was about time to add the info in here:
Pinouts for the DB15 connector on the rear of the chassis for the 8010 & 8020 (if fitted) and the 8025/8030, not using a modem card:
PIN FUNCTION
1 13.8V Switched. Run your TNC power off this
2 9V reg, switched
3 GND
4 Mic Audio.
5 GND
6 high level mic audio. (input)
7 Mic mute->4VDC will mute mic AF,0.3VDC to unmute.
8 PTT (active low input)
9 Rx FM Out, via 10k,unmuted, unde-emphasised
10 RX audio, fixed level, 550mVRMS, 470 ohm imp.
11 RX mute output - Active low, open collector.
12 Alarm In.
13 Alarm / External alert Out.
14 Speaker mute input,<2VDC will mute speaker, >8.5VDC enables.
15 Speaker AF Out, ac coupled via 56k.
Pinouts for the DB15 connector on the rear of the chassis for 8025/8030, with a modem card:
PIN FUNCTION
1 13.8V Switched. Run your TNC power off this
2 Alarm in
3 GND
4 Mic Audio.
5 GND
6 high level mic audio.
7 unknown
8 PTT
9 Rx FM Out, via 10k,unmuted, unde-emphasised
10 RX audio, fixed level, 550mVRMS, 470 ohm imp.
11 RX mute output - active high, open collector (i.e. mute open = shunt to gnd)
12 Data IN to 8030
13 Data OUT of 8030
14 unknown
15 Auxiliary option
There are some 5 sets of jumpers hiding beneath the ribbon cable of the modem interface. Link 1 is a pair, function unknown. Link 2 is a pair, and if they are 'in' it allows programming of the radio with FPP via this interface, remove these pair of jumpers will prevent programming by FPP. Link 3 is a single link on its own, function unknown.
Note that there is a document on the web relating to the SRM9000, comparing it to the PRM80 DB15 connector pinouts. This document has its origins in the UK, and has a nice table of the pinouts for the PRM80. It got the non-modem card pinouts right, but got the Australian PRM80 with a modem card pinouts very wrong - so don't use this.
Common problems encountered with the PRM80
The first problem often seen is the display flashing on and off during TX. This indicates either a drooping voltage from your power supply during TX or a voltage drop somewhere else (fuses, power connectors etc), or a high VSWR, causing the radio to shut down the transmitter as a self protection measure. Another thing to check is the power connector on the radio itself - sometimes these go high resistance (remember, even 10 ohms will be enough to limit the current to a paltry level).
A similar problem can also be caused by the antenna being too close to the radio. When the radio transmits, the RF from the antenna 'gets back into' the circuitry of the radio and swamps that circuitry. As a result, the radio will do some strange things. The fix is easy, move the antenna away from the radio and / or the remote head if applicable.
Another common problem is a flashing or flickering TX arrow symbol during TX, often accompanied by a soft buzzing or burping noise from the speaker. This indicates poor tuning of the TX VCO resonator (if modified), or you could simply be asking too much of the VCO in terms of broadbandedness. In extreme cases, the transmit arrow will fail to light up all together. It can also indicate a poor earth within the radio itself, or the shield isn't properly tightened down. This is remedied by cleaning the points where the RF board makes contact with the shield and chassis, and refitting the shield ensureing it is firmly screwed down.
No sound from the speaker on a non-CTCSS channel is a good sign that someone has tried to force the combined power & speaker connector in the wrong way, and has blown a 0 ohm jumper (looks like a surface mount resistor) that connects to the speaker line. Replacing this 0 ohm jumper with another should restore audio. In the short term, you can connect the speaker ground side to the negative of the power supply - this has the same effect.
Another unit I tried to mod would not unmute the speaker at all. I verified that the receiver worked by adjusting the volume knob (thus forcing open the speaker for a second) and heard my test signal. Programming a function button as 'squelch defeat' also had the same effect. I also noted that the RSSI was not active, despite having turned it on. Also, sometimes the Local Oscillator refused to lock. The problem turned out to be high resistance joints in the ribbon connecting cable between the control & RF boards. This can be replaced with standard IDC ribbon cable. It's a tight fit, and you need to be hyper-accurate with your soldering, but it does work. Before carrying out this tedious task, it would be best to check that the ribbon cable is sitting in the connector properly and making good contact first before deciding to replace the ribbon cable itself. If the problem is just a broken track within the ribbon 'flexi-track' cable and it is close to one end, you can cut off the broken section squarely using a sharp blade and then using scotch-brite or similar remove the varnish to expose the contacts at one end, and then refit as normal. Hopefully there would be enough length to allow you to plug it in - if not, you've not lost anything anyway, and replace it with standard ribbon cable as outlined above.
Mute 'popping' as if the receiver is overloaded or suffering interference is most often caused by the volume being set right on a 'decision threshold' setting (recall the digital nature of the volume control in the 8030s) and with a minor voltage or heat fluctuation, the radio thinks you've slightly adjusted the volume, and opens the mute in response to this. This is fixed by altering the volume control slightly, or to turn off the 'open mute on volume' option in FPP.
Another problem I have observed is during transmit, the radio 'stuck' on transmit. After turning the unit off, and on again, the display flashed on & off all display segments continuously, and no functions were active. Reprogramming the radio was not possible, and changing the EPROM did not help. The RF board was not at fault; it was removed, and the fault remained. The fault turned out to be a weird one - it was fixed by shorting out C283 (a black surface mount capacitor located between the 0.5 Farad 'supercap' and the RAM IC) for 10 seconds. Doing this clears the RAM (note: not the EEPROM or the firmware PROM). Normal operation was restored after doing this, although to discount some mis-programming of the EEPROM, I re-programmed the personality with FPP. You may want to try this if your PRM80 goes 'funny'. This was noted as a semi-common event on Dual Mode units with firmware version 4.6 - fixed by updating to version 4.7. I even had a radio where the PLL was locking at some very wierd frequencies indeed - some channels were OK, others were way off. Resetting the RAM fixed this one. It's a nice, simple, non-invasive fix to many 'funny' problems, so give it a try if yours does unusual things before reaching for the soldering iron.
Another 'microphone stuck on transmit' fault is caused by the microswitch inside the microphone getting stuck. The only way to unstick the switch is to disassemble the microphone, and allow the microswitch to spring free to it's normal position. This does not prevent the problem from recurring, and I don't have any bright ideas on this one.
One radio I found that had no TX audio from the microphone (but did produce selcall & CTCSS tones OK) had a problem with the FX365LG IC not passing the TX audio. You can replace the IC, or if you don't need the CTCSS functions you can bypass the TX audio around this IC completely. Similarly, I have seen a radio with no RX audio, also caused by a fault in the FX365LG IC, also fixed by bypassing it if not required.
Another fault of no TX audio I have seen is the microphone insert being open circuit, replacement of the insert will fix this. Sometimes an open circuit microphone insert will pick up noise or nearby AM broadcast radio stations and transmit that via the PRM80.
Various versions of heads can also cause headaches. For example, I have bought a brand new 4 digit head, only to find that it doesn't work properly on any of the PRM80s that I have played with. The symptoms are that the head does everything fine except the LCD display just doesn't work. All the buttons do what they are supposed to, the volume control works, the microphone works, you can change channels etc, but the LCD display is stuck showing a single 0. It appears that the head I have here is only compatible to a dedicated trunking radio unit i.e. 8030T. (see my comments in the trunking to PMR conversion section)
DTMF mikes will work on any head, but controller mikes which look almost identical to the DTMF mikes will only work on 6 digit heads (and hence controller mikes are limited to use on the PRM8030 or PRM8025, since they are the only units which can take the 6 digit heads/displays). You can tell DTMF only mikes apart from the controller mikes easily: the DTMF mike has a red LED in the front panel where the 'PHILIPS' label is, but the controller mike does not. Dunno about the newer Simoco mikes. Of course, controller mikes are not absolutely required on PRM8040s since they already have a keypad on the head. A DTMF mike would work fine on a 8040, if that's what you want.
If your radio does not switch on or makes a loud two tone beeping with power applied, then a likely explanation is that the unit has an incompatible program image programmed in or incompatible firmware. Try simply reprogramming the unit with your FPP, preferably with the latest version FPP you can get your hands on. If this doesn't work, try again, but half way through the programming, remove the interface cable. Then reconnect after FPP tells you that programming failed, and try programming once more without removing the cable this time. If this doesn't work, assume the firmware is wrong (i.e. trunking firmware in a single mode radio or vice versa, or possibly just plain faulty). In the worst case, it could indicate a corrupt EEPROM or terminal fault with the EEPROM or RAM. A corrupt EEPROM can be fixed, but you will need to email me for details on this.
Speaking of firmware, if you have an early version, it can be beneficial to update it; V4.7 at least for the dual mode units, and V3.6 at least for the single mode types. Minor but useful enhancements were enabled with the later versions - for example, being able to adjust the mute without disabling the RSSI first, or an increase in the rate that the channels are stepped through if the channel change buttons are held down for more than two seconds - things like that. You may also need to re-align your mute for best weak signal performance if you had a very early firmware version. When updating or replacing your firmware, first read in your personality of the radio using FPP and save the file (this is a good thing to do anyway - just in case!) Then power down the radio, replace the firmware, and short out the RAM backup capacitor by shorting C283 as noted above. Then power up the radio - if you get a two tone beeping, simply reprogram your personality using FPP. If the beeping doesn't go away, then restore your original firmware (you did keep it, didn't you?) and reset the RAM again. That should get you back to square one.
A common question asked by people is 'my 8030 radio doesn't seem to work - when I switch it on, it shows "n1" and a number and then I can't do anything with it'. This means the radio is a dual mode unit, and has powered up in trunking mode. To place the radio back into normal "PMR" mode, when the radio is first switched on, quickly press the left hand function button on the head, and in response to this, "n1" flashes. Now press the left hand up/down buttons until "p" is shown and leave it there. Then after 5 seconds or so, switch off the radio and then on again. If your radio is already displaying a flashing "n1" at turn on, there is no need to press the left hand function button in the above procedure, but you do need to press the up/down buttons before "n1" disappears. Apparently this procedure doesn't always work, so you may have to fiddle around with the function buttons a bit to change the mode, but the display sequence will be similar.
I found one radio which no amount of button pushing encouraged the flashing 'n1' to appear. The answer here is to use the PRM80 trunking FPP to turn on the 'power on network select' feature. You may as well also set the 'power on network' to PMR mode while you are at it, and you will never have a problem with the radio powering up in trunking mode ever again. The PRM80 trunking software is available on one of the web pages listed below.
Don't try to convert a 8020T or 8025 or 8040 local mount radio into a remote by simply plugging in a remote cable to the mic socket, and then trying to attach a remote head to the other end - it will cause damage to your radio. Local to remote conversions are possible for the 8025 - but you will need to have plenty of patience with soldering tiny components and wiring! For the 8025, remove the 2.2k resistors R383 and R350, and remove the 470 ohm resistor R311, and add the 0 ohm jumpers R352 and R384, and then reprogram the radio for remote head operation. 8010s and 8020s can't be 'remoted'.
Apparently many versions of PRM80s had some problems with electrolytic capacitors - check that all your little silver surface mount electrolytic capacitors are OK, especially on the RF board near the MC3361 or MC3371 IC if you have squelch or volume problems on your early PRM80. Leaking electrolytic capacitors often betray themselves by a dark blue or brown stain around them on the PCB as shown in leak.jpg picture file. As an example, on the RF board, C466, the squelch filter cap commonly dries out or leaks causing squelch problems. Replace this with an equivalent value (1.0 uF) tantalum capacitor. This cap is located on the RF board, and is the small metal 'can' right at the front edge of the board, half way between the flexi-track connector and the pair of 21.4 MHz IF crystal filters.
No matter where a leaking SMD electrolytic capacitor has been found, it should be removed and replaced with a tantalum type (which are not prone to leaking) and before fixing the replacement capacitor to the board, you should clean off any contamination. The stuff that leaks is corrosive and slightly conductive - both causing DC signal leakage into or out of other circuits and eating the tracks on the PCB. You can clean the contamination by carefully scraping it away to expose bare copper on the PCB tracks where it has spilt. Clean the area with a solvent and wipe dry, and brush any debris away to make sure. Then tin over any exposed (bare copper) PCB tracks with solder to protect them. If you have PCB circuit laquer then spray some of this on, too.
Solder flux can effect the operation of the RF and mute sections of the RF board. If you have some problems with the TX or mute sections, and maybe the RX section, and you can find no other or obvious problem, then look to see if there is any solder flux residue. This is particularly relevant around the TX power amp devices. I prefer to gently scrape flux away rather than use a commercial flux removal spray.
A problem that I have come across with the remote head 8030s is no power being supplied to the head - the radio will not switch on. A check of the voltage regulators indicates that they are working, but at pin 4 of the remote interface (as per the diagram above) shows zero volts or maybe only a few volts - it should be around 9 volts. There is a switching transistor that takes 9 volts to this pin 4, and that switching transistor is under control from the microprocessor. Each time I have observed the fault, it is either the microprocessor not turning on the switching transistor, or the switching transistor has blown (and close examination shows a tiny burn mark on the culprit transistor) that appears to be the cause of the problem. Why the microprocessor has decided not to turn on 9 volts to the head I do not know, but the cure is simple. Just take a short length of wire from the positive output of the 9 volt regulator and take it to pin 4 of the remote interface connector, so the head permanently has 9 volts supplied. Don't worry; you will still be able to turn the radio off and on in the normal manner.
Low sensitivity and low output power can be caused by a dry joint or fracture of the solder at the antenna connector. Resolder and add a bit more solder to cure this one.
One other problem that is more tricky to find is the 9 volt RX "switching transistor" sometimes becomes 'weak' and manifests itself as all manner of wierd things happening with the receiver - particularly mute problems of not opening or closing, or the RX being apparently unstable. You would never know it by measuring the 9v RX rail, though, it still shows 9 volts unless the problem is starting to become terminal in which case you might measure 8 volts or less. The faulty transistor is located on the control board near the 9 volt regulator and is a BC808, but can be replaced with any other compatible type.
Here are some hints kindly donated to me by Scott:
The SMC electrolytic caps are renowned for leaking. The best solution for this is to replace them with tantalum or ceramic types.
Chopping or loss of mute - change C458 to 220n, C466 to 1U/10v (C466 location given above, C458 on the RF board location is the metal can almost between the ceramic filter and the 20.945 MHz crystal. Later RF boards had changed this to 220n by using two surface mount caps soldered double decker style or one single surface mount type, so there's no need to go changing this if this is what you find instead of an electrolytic)
Low Rx audio - as above plus change C216 to 2u2/10V (C216 is located on the control board, fairly close to the -9.0 volt regulator, just below the main power switching transistor. There's two metal cans here side by side: C216 is the one closest to the legs of the -9.0 v regulator)
CTCSS on Rx audio 8010/20 only - change C246 to 1u/10V
PLL noisy - change C528 to 1u/10V and C470, C492 & C552 to 2u2/10v
Distorted Tx audio - change C552 to 2u2/10V.
Some of the symptoms of the RF shielding problem are distorted CTCSS or noisy
or intermittent TX. The fix is to fit a strip of aluminium tape around the front right hand
edge of the radio board as well as fitting washers under the shield screws and ensuring the shield is firmly screwed down. (I have also noted a strip of aluminium adhesive tape near the power connector on the side of the radio, bonding the shield to the chassis on many 8030s)
Sometimes the black strip around the board needs to be cleaned with a fibre glass pencil or rubber to improve the shielding.
The 'usual' problems that appear with CBs can also be observed on PRM80 radios that have been handled carelessly or by someone who doesn't know what they are doing. Fuses that blow all the time indicate that someone has reverse polarised the power supply, and the protection zener diode is now short circuit. Replacing the diode with an identical type should restore things - so long as the person who connected the power backwards shut off the power and didn't replace the fuse with a bigger one, or worse, a screw or lump of foil! (ARRG! Don't you just hate it when people do things like that?)
Scratchy TX audio can be one of two things. The first is applicable to the controller microphone only and is identified by a windy, scratching sort of sound on TX, almost as if there is a broken wire in the microphone cable. This is actually caused by a few capacitors in the microphone handset leaking DC through them. The fix is to replace C2 and C3 inside the microphone with 1uF tantalum capacitors. C2 & C3 look like tiny black oblongs with '105' printed on them, about the size of a pin head. You can use 4.7uF tantalums if you wish to have a little more bass in your transmitted audio. With the mike cord facing down, and the PCB swung out of the mike case to the left, near the bottom right side of the PCB where the yellow wire attaches to the PCB is a small black 1mm x 2.5mm surface mount 'box', marked C3 on the PCB. Replace this with a 1.0 to 10uF tantalum. Also, there will be an identical SMD small black 'box' marked C2 near where the black wire attaches to the PCB, about in the middle of the board. Replace that with a 1.0 to 10uF tantalum, too. You might find it easier to work on the PCB if you remove the clamp holding the microphone cable in to the case.
The second scratchy TX audio is identified by a sharp, harsh scratch, and is a sure sign of the microphone cable having an intermittent open circuit in one of the wires. Replacing the microphone should fix the problem. Alternately, you can replace the mic cable itself, but I'd recommend using a genuine Philips / Simoco cable assembly - just using a standard CB microphone cable with a crimped on RJ45 connector won't last very long. An interesting thing is that Philips / Simoco don't sell microphone cable assemblies - they only sell complete microphones, which is consistent with their policy of microphones not being a repairable item - only replaceable. You would need to hassle a radio repair shop to see if they have any faulty microphones left laying around, and scrounge one of those, and hope that the cable in that is good, and that the mic was replaced due to faulty electronics or a faulty insert. If replacing the microphone does not fix the problem, take a look at the remote cable for those who have the PRM8030 or 8040.
If you are ever removing or replacing the RF shield, or doing soldering on the radio of any description, turn off the power and remove any power plugs / cables first. This will prevent any accidental shorting to earth of any active power supplies or components that may have power applied to them - even if the radio's power switch is turned off.
If you have your PRM8030 or 8040 installed in a mobile, and the display starts to reset or flash everything rapidly, switch it off fast! Then go looking for damage to your remote cable (i.e. head to body) - my mobile unit exhibited this problem and found that the cable had been pinched underneath a car seat, shorting the 9 volt power line to earth. Luckily no other damage resulted, but the moral of the story is to route your remote cables carefully where they are not likely to receive damage.
Another fault was given to me saying 'the radio has really bad TX and RX - even my old Uniden 001 works heaps better'. Turns out there was nothing wrong with the radio at all - it was the PL259 to BNC adaptor the guy was using was short circuit. Remove the adaptor for the Uniden and all was fine, put in the short circuited adaptor for the 8030 and of course the receive and transmit will go out the window. In any case, you shouldn't be using an adaptor of any type - I proved this the other day when RX'ing some really weak signals with an adaptor and a short coaxial 'tail'. Remove the adaptor and tail, and the signal became 50% more copyable. A friend also demonstrated why you shouldn't be using adaptors - he had two 'elbow' adaptors to help make a neat transition of cable through a wall. He was loosing about 2 watts of the 5 being transmitted by these adaptors. That is nearly 3dB loss through those adaptors - yuck!
Yet another 'low sensitivity' fault was cured by cleaning the antenna connector (both on the PRM80 and the antenna connector on the end of the coax) that had a reasonable amount of dirt and contaminants in it. I used a special swab on a stick with isopropyl alcohol to do the cleaning of the BNC connector body, and a shaved down match stick dipped in the IPA to clean the centre contacts of the connector.
One recent fault I had was very simple to fix. The display was slowly flashing all segments lit up. The radio was a 8030 remote dual mode, with the little FSK daughter board. One of the little wires leading to the FSK daughter board was pinched underneath one leg of the EPROM which had recently been replaced. Simply remove the EPROM, re-run the wire away from the EPROM socket, reset the RAM as detailed above, re-insert the EPROM and away you go. Reprogramming with FPP may be needed.
Recently, an 8030 was observed to be 'frozen' on power up - it would just sit there with the power on message and do nothing else. This was fixed by reading and writing the radio configuration with FPP.
I have seen the occasional fractured solder join from the RF board to antenna connector. If you have the RF shield off, it might be worth re-soldering that point no matter what. If the fracture is bad enough, there will be enough capacitence for the receiver to work, sort of, but the TX will get quite upset.
Another fault with the mute that didn't respond to the 'usual' fixes above was fixed by adding a 0.1uF capacitor in parallel to C267 the little brown SMD capacitor that lives near pin 4 (next to the chamfered corner) of the FX459 IC, near the front of the control board - this capacitor is identified by one of it's 'legs' going to ground foil of the PCB.
PRM80s are noted for occasionally doing some weird things - like resetting themselves, changing channel rapidly by themselves, lighting up or flashing all segments or missing digits - things like this are usually cured by a simple power off, wait 5 seconds, and then on again. If not, remove the power supply to the unit entirely for 10 minutes, reset the RAM as detailed elsewhere in this file, and reconnect power.
It's also a good idea to try and keep power connected to your PRM80 (all versions) all the time - this will keep the RAM powered up retaining your memorised scanning channels, and will improve stability on powering on when you do use the radio.
Here are a few spare parts that Rockby keep that are used in the PRM80 series:
MRF646 (SRFH1068 is equivalent) RF power transistor for UHF versions, about $46 ea.
HY62256A RAM as used in PRM8030, about $7
CML FX365LG CTCSS IC, about $10
TDA1519A audio amp, about $7
PCF2100T display driver for 4 digit head, about $5
MC3371 NBFM IF with RSSI IC, about $4
Mic bracket with magnet, part no 12249, about $1 ea.
And finally, some common spares that you can order from Simoco:
8025/8030 Microphone connector cover (very commonly lost) : 3513-901-11411, about $5 ea.
8020/8025/8030 Clear plastic display lens : 3502-310-42940, about $3 ea.
and from Dick Smith Electronics:
Power connector : P5120 for about $4. Make sure no &^!$@ has removed or short changed you of the vital female pins in the packet. Its the same type as used on computer hard disk drive power connectors. Molex and Utilux style connectors should also suit - if you can find them.
If there is a serious fault with your radio that is beyond your expertiese to repair it may need professional help. If this is the case, and you need to send your radio to a repair company, do be very careful. When looking for a company to repair your radio, you should ensure that the company has experience with Philips / Simoco PRM80 equipment and that they have the backup support to get spares should they need to source them. Also get the company to provide an estimate for repair, or better yet a quote, and get it in writing. At the very least, keep a record of telephone conversations by writing down the name of the person you are speaking to, the substance of the conversation, time and dates. If you can record the telephone conversations that would help, but remember you must inform the person at the other end if you are recording the conversation.
If the estimate or quote is high, you have to ask yourself is the radio worth repairing? Would I be able to get the same radio on the second hand market for less than the asking repair price? Also make it very clear that you do not want to have the radio repaired without your final authorisation.
And when sending your radio to a company that is not local, send it with insurance and some way that you can get proof of delivery, and have the company at the other end do the same on return. You just would not believe the number of shonky companies out there who claim that 'oh no, we never got that' (and they did) or say 'oh yes, um, er, we sent that today' (and don't send it until next week, if at all).
Just as an example, I recently had my 8040 repaired by a very reputable company. They quoted $50 for the repair, saying that they would offer a good repair price considering the 'hobbyist' nature of the radio (a 2 metre ham rig). A month went by without the radio being returned to me, and further enquires revealed that the 'quote' had since been changed to $200 (to which I reluctantly agreed to), and a month later had gone up to nearly $500. I felt like saying 'no thanks, just return the radio to me' but they had already repaired the radio without my agreeing to the increased quote. So it was either put up the money or lose the radio - they made it quite clear that I wouldn't be getting the radio back unless I paid their price. And remember, this was from a reputable company. Admittedly, they did offer a $100 discount when it was pointed out that for the price of the repair I could have purchased a complete replacement unit (8038 conversion kit), but still putting up a 'quote' twice and going ahead without my consent on the last increase is inexcusable business practice. And to top it off, they took nearly three months to repair it. Unbelievable! Don't get burnt like this! (And you wonder why I'm paranoid to the extent of writing everything down and recording such telephone conversations now??)
If you are going to use your PRM80 in a mobile...
It has been found that the modifications for retuning, especially those that involve adding trimcaps, can become unreliable over time if used in a car etc. Common problems have been trimcaps breaking or solder fractures, and adjustments vibrating out of alignment. This can be remedied two ways. First, to prevent vibration causing mis-adjustment, use a dob of hot candle wax on the trimpots, trimcaps, and other adjustments to keep them in place. To prevent solder fractures, ensure good solder joins (not necessarily by using more solder which will be detrimental to RF performance- just make your joints clean & strong), and ensure the trimcap does not make contact with the shield, which is most important. Having said that, my PRM8030 has been bouncing around, unsecured, underneath a seat in a 4WD for over 2 years without the candle wax to freeze the adjustments without problems (the trimcaps were stiff enough not to warrant the wax)
Another possibility is to use physically small-as-you-can-find ceramic disc capacitors in place of trimcaps. What you will need to do is to either install the trimcap and once adjusted, carefully remove and measure it's capacitance at that setting and replace with a disc ceramic as close to that value as possible, or simply try installing disc capacitors on the resonators of various values between 2.2 and 6.8 pF until you find what works, and what does not, each radio will be slightly different, so I can't give any hard & fast values for each resonator. I found that a combination of 4.7pF on the front-end receive resonators and 3.3pF on the RX & TX VCOs worked pretty good on most occasions for a W4 to W1 conversion, but bear in mind you MUST tune the tracking gain adjustments professionally (i.e. with a signal generator and CRO). I have found at least one radio that did not respond well to 4.7pF disc ceramics on the RX resonators, each resonator appeared to want a different value capacitor, so in this instance I used trimcaps to effect the modification. Sometimes the 3.3pF on the RX VCO isn't quite enough to shift the RX bandwidth down low enough to cover police UHF RX, so try 3.9pF or even 4.7pF if this is the case. When selecting your disc ceramic caps, try to find as physically small as possible types - the types that are about the size of a match head are ideal, and the next size up (about 4 or 5mm in diameter) are OK, too. Avoid any larger sizes. And when installing them, keep the lead length to a minimum - the leg that solders to the resonator body need only be 5mm long with the body of the capacitor right up against the resonator. The other leg that solders to the centre 'plunger' also only needs to be 5mm long at the most.
Of course, using disc ceramic capacitors instead of trimcaps means that you will not be able to set the VCOs to the exact coverage that you want, nor will you be able to adjust the front end resonators for absolute peak performance like you could if trimcaps were installed, but offsetting this slightly is the fact that fixed disc ceramic capacitors have a higher Q than their trimcap cousins, and some of the loss of performance from not being able to precisely peak the adjustment is partly gained back by the higher Q factor. This does however mean that you will be relying on the PRM80s internal voltage tuned (i.e. tracking) front end feature to keep RX performance peaked across the coverage, and as I have found out, if you are covering large chunks of bandwidth, this is not always optimum. Having the trimcaps means you can at least tune for best compromise despite the tracking adjustments. I have found that very carefully aligned trimcaps on the front end and tracking gain adjustments can yield 1.5dB better performance than if using fixed disc ceramic capacitors on the front end.
So, in summary the trimcaps offer the advantage of being able to be adjusted precisely for peak performance, and if necessary tuned for compromise performance across an abnormally wide bandwidth (say more than 15 MHz), with the disadvantages of not being as robust as the fixed value disc ceramic capacitors. The fixed value disc ceramic capacitors have the advantage of being cheaper and simpler to install because they don't have to be tuned, and being more robust suited to a mobile installation, but have the disadvantages of not being able to be peaked for absolute maximum performance (very slight performance disadvantage) and will not lend themselves to 'compromise tuning' if used in a wide bandwidth application.
One thing I have quickly investigated is the effect of the higher Q of the disc ceramics on available bandwidth of the VCOs. Adding a trimcap definitely does reduce the bandwidth that VCO can cover (recall my comments above about a 'native' band board being able to cover 50 MHz or so on RX, but when modded with a trimcap, this reduces to 40 MHz), so I wondered if a higher Q fixed value disc ceramic will yield a better bandwidth? Well, unfortunately no, they do not appreciably increase the bandwidth the VCOs can cover. Yet another thing to think about when deciding to use trimcaps or disc ceramics. (If you want better UHF bandwidth and the ability to keep a constant sensitivity level across the band, look at a non-trunking Tait T700, with the 755 model wideband receiver and wideband tracking TX PA - 450 to 520 MHz with ease, and if tuned for a very narrow IF bandwidth they become a super hot receiver; -121dBm for 20dB quieting (approx 0.135uV for 12dB SINAD !!), but at this narrow bandwidth, they do moderately clip the audio of most transmissions; returning the bandwidth to normal yields -122dBm for 10dB SINAD)
Another thought that may yield yet more performance advantage, however slight it might be (and it would only be very slight - I'm guessing maybe <0.25dB performance advantage) is instead of fixed value disc ceramics, obtaining fixed value surface mount components such as 3.3pF and 4.7pF capacitors and solder them across the resonators at the appropriate locations. Again, with this method you don't get the advantage of being able to precisely tune the circuit as you could with a trimcap, but you gain the same advantages as you do with disc ceramic capacitors, only the advantage is magnified slightly due to keeping all components surface mount. But bear in mind that the gain is only very slight, and if you do manage to get an extra dB of receive performance, that only equates to 1/6th of an 'S' point. Still, a dB here and there soon adds up, and if you manage to save 3dB (use Belden 9913 coax or even Heliax instead of RG213 or use RFIs 'Cell Foil' coax instead of RG58 if in a mobile, use the best quality connectors you can find rather than the average quality ones, never ever use adaptors, do your tuning adjustments really carefully and slowly, it all starts to add up) - it is like making your radio twice as sensitive if you think on a linear scale.
My very latest thoughts are that if you are converting a W4 unit to cover UHF CB and Police RX only, which probably covers 95% such conversions, that it is easiest to use 4.7pF disc ceramics, the physically smallest you can find, on the 5 receive resonators and the RX VCO resonator, and use a 3.3pF or 3.9pF disc ceramic on the TX VCO resonator. This minimises cost, and simplifies tuning, so long as you have the correct equipment, of course. For those who demand the absolute very highest performance, squeezing every last drop of performance out of the front end or for wider coverage applications, you should be looking at using all trimcaps, as mentioned above. If the unit is intended for harsh mobile use, then definitely go for all disc ceramics, as I have had two reported failures of the trimcaps (substrate break-away) in mobile use, although I have had 3 others in mobile use for over two years with no problems at all. No matter which way you go, you will require proper tuning of the tracking gain adjustments, though, so bear this in mind.
Other web pages to visit:
http://skinny.8k.com/prmman.html has extracts of the service manual for PRM8010/20
http://skinny.8k.com/prm.html has general info regarding the Philips PRM80 series
http://skinny.8k.com/prm/ has programming software for 8010, 8020, 8025,
8030 & 8040 and trunked versions. You will need to email Skinny for the password to the .zip archives. Turn off any
download accelerator or manager, otherwise it will not work.
http://members.optushome.com.au/mrskinny/prm/ mirror site of above.
http://ozradio.wireless.org.au/radio.htm Bens radio related page, alignment info for the PRM8030 (suits 8040 too). The older firmware images and FPP
software that used to be there are currently removed, but
may be put back soon.
http://www.btinternet.com/~compton/prm80.htm Cracked (no frequency entry limits)
versions of FPP for 8010/8020 and 8030.
http://prm80.8k.com has some info about programming the PRM8030
(recently unavailable)
http://www.rockby.com.au occasionally has some PRM80 bits for sale (look in
the monthly specials, but you can phone up and ask for stuff that they might hold, but is not advertised)
http://keycom.d2.net.au/index.html Keycom, who has heaps of radios & spare parts for
sale, including PRM80 spares. The email address is: info@keycom.com.au
http://groups.yahoo.com/group/Australian_PMR/files/Simoco/ and
http://groups.yahoo.com/group/PRM80-Series/files/ has programming software
http://www.owenduffy.com.au/electronics/rpi/rpi.htm programming interface info
(recently unavailable)
http://groups.yahoo.com/group/PRM80-Series/files/FPP5.7/ FPP 5.07 for PRM8025, 8030,
and 8038 (PMR, dual mode or
trunked only)
Thanks from the author:
Such a large document doesn't simply happen - it takes time, experience, experiments, and invaluable advice and help from others. I would like to thank the following people who have assisted in the creation of this document:
Cambo - for hosting this information on www.geocities.com/ch8users/
Mick - for fearlessly providing radios for me to learn new modification tricks.
Scott - for enduring my endless email requests for information & help.
Ben - thanks for all the advice, especially with faults & rectification. I still owe you a
return favour for the CTCSS board...
Skinny - for providing the software files that helped me learn about the features on
the 8040 & 8020 & 8010, and the pictures of the 8020
RiO - for more advice & info on SelCall setup, and answering all my dumb questions
John - for encouraging words
Ivan - the fellow who parted with his 8030 to pass on to me - the one that started it all
And anyone else who has contributed that I've forgotten or wished to remain anonymous.
Requests from the author:
To provide more complete information in this document, I would like to try and find the following:
A schematic and any 'official' documentation relating to a genuine UW or TU band RF board.
A description of any add-ons for the PRM80 series - things like any options, external modules etc.
A high resolution picture of the 8025 head internals.
Anyone able to help with these?
Possible future developments:
Garry Cratt from AvComm has a project underway to turn the VHF 8030s into a high quality AM aircraft band receiver. No further news on this is available as yet, Garry is flat out with other things at the moment.
Another project suggested is a "two radios, one head" twin band modification for 8030s. The 8030 radio doesn't need a head to continue operating on RX - you could therefore have say a T band UHF radio and a A band VHF radio operating as a pair, and have the head switching between the two, creating a 2 metre and 70 cm twin band radio. You would only need to switch 3 wires at most: the TX & RX data lines, and maybe the TX audio. You would also need to keep the on/off control line held 'on' for the radio not presently being controlled by the head to keep it's RX alive.
The reverse of the above is also possible - one radio, multiple heads. In fact the feature is built in to the 8040, but I have no information on how to actually do this.
Someone else is working on a DIY microcontroller setup to drive the RF section of the PRM80 & PRP80 series - you could potentially set up your own custom user interface with custom features eg: emulated VFO, scanning more than 16 channels at once, direct PC control, things like that. If the project bears fruit, it may appear on this web site.
Footnote from the author:
The information presented here is to be used by you entirely at your own risk. I have not verified all modifications listed, I simply don't have the time or resources. However, I have verified maybe 95% of the mods, and I am reasonably confident that the remainder should all work as described. Nor will I be responsible for how you use this information, or any consequences resulting from its use. Some (well, most, actually!) of these modifications will void the type approval of the radio for all but amateur use.
This information was put together with the intention that all may benefit from it - the information is made available to you free of charge, and that is the way I want it to remain. Many hundreds of dollars & hours of effort have gone in to these projects to experiment and learn to produce this document. I wouldn't be too pleased to learn that someone has used this information for blatant profiteering. By all means, help others with their hobby, but do it for a reasonable fee.
Most important of all, if you do learn of an error in my information or find a better way of doing things, or have some more or additional information to suggest, please share it with us! E-mail me at: mitaux8030@hotmail.com and I will update this file so that we all may benefit.
I would also welcome suggestions as to what you would like to see added to this file to make it more useful. Any reasonable suggestion will be looked at.
An earlier version of this file was published in the Australian magazine 'Radio & Communications' April & May 2001 issues and there were some minor editing changes to make it suitable for publishing. There were also some errors in that published version. Be assured, you are reading the very latest, unedited and as far as possible error free version of this document.
This document was created on a fairly modest PC with Windows95 and Wordpad. Persons using an earlier or later version of Word may find that the formatting and tabs are all over the place and maybe the embedded picture of the RJ45 pinouts is missing (I supply this picture separately, too, so you won't miss out). I can only apologise, but it isn't my fault.
Version history:
1.0 Initial investigations, mainly centred around W4 conversion to W1 band
1.1 Added in other info relating to other band units and RF board swapping
1.2 Added info relating to tuning, other mods, transmitted audio improvement
2.0 Added info relating to SelCall decoding & display, photos, discuss common problems, verify
much of the untested info, programming out of band freqs, a virtual rewrite from start to end.
(It was this version, with some editing, that was printed in Radio & Communications
magazine, April & May 2001 issues)
2.1 First public release, added in identification info, verified out of band freq ranges, and added
interesting web pages to visit. Also managed to get binary images of firmware.
2.2 Corrected minor errors (grammatical mainly, no technical errors found so far)
2.3 Some more minor corrections & additions. Also added in version history for interest.
2.4 Added in info relating to external keypad, other minor improvements for readability.
More identification info & a new web page to visit.
2.5 Second public release. Added more digital camera pictures.
2.6 Some more common faults added, and another web page to visit
2.7 One very minor update made, and a few wording changes
2.8 Scrambler installation info added.
2.9 Discussion of trimcaps versus disc ceramics for W4 to W1 conversion.
3.0 Added in & acted on user feedback. Give me feedback so I can improve my info for you!
3.1 Added programming interface hints & tips, and a simplified schematic diagram.
3.2 Yet another minor update regarding W4 board availability, adjustments for RF power and
comparing VCO bandwidths on a W4 board with trimcaps Vs. Disc ceramic caps, and
some other miscellaneous updates.
3.3 Even more photos and some new info added.
3.4 More faults & fixes added.
3.5 More identification info added.
3.6 Info relating to UW band units, typical sensitivity values added.
3.7 Third public release. Short discussion on trunking to PMR conversion.
3.8 Minor correction: I can't count! (need 4 x 10uF caps for the DIY prog. interface, not 5!)
Also some info on firmware interchangeability.
3.9 Added DB15 connector pinouts, and tidied up the firmware zip file.
4.0 Corrections. 8020's don't have firmware - my mistake. Also suggested using surface mount
components for modifications.
4.1 Added info on hacking the EEPROM image for further out of band frequency entries etc.
Also found that 6 metre conversion is not really feasible.
4.2 Added info relating to my first experience on converting trunked 8020 to a conventional unit
Also updated some supplier info, web page updates and more info added to firmware zip file.
4.3 More pictures, more faults info, firmware file update, and a short piece on the 8040.
4.4 Some more pictures, more faults, and a little bit of an update on the tuning.
4.5 Update on some moved web pages
4.6 Refined my thoughts on trimcaps vs. disc ceramics vs. surface mount components.
4.7 More info on getting the programming interface to work.
4.8 A few wording changes, and minor updates all over the document.
4.9 A few minor corrections that I missed in 4.8.
5.0 An update on UW band units, and a slightly more logical layout of the sensitivity info.
5.1 A few more photos and some minor changes to make things more consistent throughout.
5.2 A new file, detailing manual conversion of UHF police frequencies to VHF frequencies when
adding out of band freqs to W1 only units, and added a user review of the PRM80 series of
radios, mainly concentrating on 8030 remotes, and mainly for Australian UHF CB use.
5.3 A few minor corrections, and compared the 8030 with the Sawtron 999.
5.4 A few more minor corrections
5.5 A new fault to consider & a cross band repeater cable to connect two PRM80s back to back, and
increasing the channels on a PRM 8010
5.6 A few new faults added, and more info on trouble shooting the programming interface.
5.7 More info on 8010 to 8020 conversion, and a few minor updates here & there.
5.8 A few minor new pieces of information.
5.9 Links updates and a new diagnostic program for the 8010 & 8020.
6.0 Re-arranged the order for tuning a bit, and a few updates on firmware & EEPROM corruptions and
DB15 pinouts plus lots of little corrections, clarifications & additions.
6.1 More info on trunking to PMR conversion, and a bit on microphone cord replacement.
6.2 8020s definitely can not have more than 64 channels.
6.3 A little bit more on the 8040.
6.4 Some more information about out of band frequency calculations
6.5 Added some more fault fixes, and a little more on the 8010 to 8020 conversion.
6.6 More happy users quotes about how the modified W4 8030s perform and a new picture added.
6.7 Another picture, and the review finished.
6.8 Keycom web page updated.
6.9 Scanning more than 16 channels at once info added
7.0 PRM8040 modification upgrade from 8030 done in more detail, 8040 firmware images added and
8040 head internal pictures added.
7.1 More links added.
7.2 More faults added, 8010 & 8020 starting hardware codes added, Torx tool use tips, 8010 to 8020 conversion update, TX audio modification for better treble response added, and some more notes
on RF board swapping, and the price of PRM80s on the second hand market has dropped right
down.
7.3 Some spare parts are held in stock by Rockby could be useful in fixing PRM80 faults.
7.4 Spelling mistakes fixed.
7.5 Keycoms email address confirmed and tidied up the 8030firm.zip file, as well as improving the
firmware explanation for the 8040.
7.6 Rockby have the lithium backup battery as used in the 8040 control head.
7.7 Picture of 8038 added, discussed one W4 radio that wouldn't modify with the disc ceramics and
required trimcaps, and added info on removing the microphone cover.
7.8 A new fault added, tested a narrow band genuine W1 and compared the Tait 2020 with PRM8030.
7.9 Updated the sensitivity measurements to compare to other radios, and details on improving the
UHF versions in band sensitivity very slightly, and a few alternatives to the R4001 trimcap found.
8.0 Clarifications on 8040 programming
8.1 Added band designation information, more on getting your programming interface to work, and a
few new fixes to that damned 'beep-boop' error tone.
8.2 Heard that the E band units can be dropped to 54 MHz (6 metres) but no specific information yet.
8.3 Added info on locating the EEPROM (so it can be reset), more 'band identifier' info added, some
minor corrections, and a proposed method for 'twin banding' two PRM8030s together. Also fixed
the spelling.
8.4 Clarified the procedure to change hardware codes on the 8010, 8020, 8025 & 8030. Also more
clarifications on 8040 programming, and some things to consider if you have a 'worst case
scenario' fault. And maybe a custom PIC controller project on the horizon?
8.5 A few minor bits updated, and if you've got a RF adaptor, get rid of it!
8.6 More on programming & using the 8040, and a previous fault better explained.
8.7 A few final tweaks to the 8040 section.
8.8 Added info on the PRM80 power connector pinouts and a new fault added.
8.9 New URL for cracked (no freq entry limits) for FPPs for 8010/8020 and 8030 (remote, single mode
PMR types only)
9.0 Added a section for absolute beginners on the PC programming process.
9.1 FPP V5.07 is in the yahoogroups file area, and a little more on selcall decoding.
9.2 Another hint on getting FPP talking to your radio added, and more on the firmware & 6 digit heads.
9.3 A new picture of leaking electrolytics added, by far the most common fault to look out for.
9.4 Another mute fault fix added and more clear instructions for fixing the 'windy' microphone problem.
9.5 Added info on some of the modem interface jumper links.
9.6 Added photos of the PRM80 series handset and the DCU80 control panel and a new fault fix.
9.7 Quite a few more faults & fixes added.
9.8 More info on converting 8020Ts to PMR mode. You defintely can't use the 8020T display after
conversion - either find a 8025 display or 8030 remote head. Also added a pic of a 8025 display.
9.9 Some new faults & fixes added, and re-arranged the programming interface information to be
slightly more logical.
10.0 More info on using the modem card for programming PRM80 series units.
10.1 Minor modifications, and the latest (albeit beta release) firmware for 8025, 8030 & 8038 added in the
8030firm.zip file.
Unless something dramatic comes up, I plan for this to be the last update to this file. (I shouldn't say that! I said this back at V4.9!) The exceptions might be to correct errors, act on feedback, adding more pictures or if some new development happens that is of relevance to PRM80 users. I think this information file has reached a point of maturity, enough so as not to require any further additions, which would probably be of limited interest or value to most hobbyists playing with the PRM80. Enjoy!
Cheers,
Michel Mitaux