Search found 433 matches

by The Defpom
Sunday 27th Oct 2019, 11:02
Forum: CB Radio General
Topic: Is there anyone out there
Replies: 4
Views: 7151

Re: Is there anyone out there

The forum is very quiet these days yes, it certainly isn't anything like they way it was 10 years ago when it was busy.
by The Defpom
Wednesday 7th Dec 2016, 21:11
Forum: CB Radio Repair and Troubleshooting
Topic: Uniden 980ssb
Replies: 4
Views: 7449

Re: Uniden 980ssb

I would just try replacing the diode with a new one and seeing if it works.

I don't have any info such as diagrams for them yet.
by The Defpom
Friday 12th Dec 2014, 7:55
Forum: CB Radio Repair and Troubleshooting
Topic: GME Electrophone final replacement
Replies: 12
Views: 16699

Re: GME Electrophone final replacement

It is a 2SC2078, I do not know if RS stocks them.
by The Defpom
Saturday 7th Sep 2013, 14:45
Forum: Shout Outs
Topic: I'm famous
Replies: 7
Views: 19531

Re: I'm famous

It's good to see you are still around!
by The Defpom
Tuesday 15th Jan 2013, 20:43
Forum: CB Radio Repair and Troubleshooting
Topic: Electrophone GME TX840B SSB Low Power
Replies: 1
Views: 4926

Re: Electrophone GME TX840B SSB Low Power

I dont have any info on that model myself, but it sounds more like a bad capacitor (or a few of them) in the audio path, effectively hi-passing the audio, cutting off the lower tones.

An incorrect SSB offset calibrations could also be possible, resulting in the frequencies being cut by the IF filter.
by The Defpom
Tuesday 15th Jan 2013, 20:39
Forum: CB Radio Repair and Troubleshooting
Topic: Cb not receiving
Replies: 3
Views: 6881

Re: Cb not receiving

I suspect that it has overloaded the front end of the RX chain, most probably the shunt diodes, D1,D2,D19,D20.
by The Defpom
Monday 12th Mar 2012, 9:49
Forum: RadioMods Members Assistance
Topic: The Old Browning Ping
Replies: 2
Views: 5154

Re: The Old Browning Ping

Sounds like it needs to go to the tx from the mic, I would have to check it though
by The Defpom
Thursday 22nd Dec 2011, 23:11
Forum: CB Radio Modifications
Topic: lincoln HR2510 MRF455 pcb
Replies: 3
Views: 8852

Re: lincoln HR2510 MRF455 pcb

Mount the new MRF455 / SRF3775 on the rear panel on the bottom of the radio instead of the top, much more room there :-)
by The Defpom
Monday 28th Nov 2011, 10:31
Forum: CB Radio Repair and Troubleshooting
Topic: hr2510 president Lincoln CPU
Replies: 26
Views: 28269

Re: hr2510 president Lincoln CPU

It would pay to have a close look at the reset circuit which does a reset every time the radio is powered up, I have seen them fail to produce a sufficient reset pulse time, causing the MCU to not correctly reset. The MCU reset pin is 49, the circuit consists of Q316, Q317, IC314 and a dozen other m...
by The Defpom
Thursday 24th Nov 2011, 20:42
Forum: CB Radio Modifications
Topic: COBRA 148 GTL ADDING FREQ. COUNTER
Replies: 7
Views: 12289

Re: COBRA 148 GTL ADDING FREQ. COUNTER

The only way to read the TX and RX freq on a radio is to hook into the offset oscillator, however, this will not give you the on channel frequency, as it would need to be mixed with another frequency (to match the radios IF), for instance if you hooked into the 148, you would be seeing a 34MHz frequ...
by The Defpom
Thursday 24th Nov 2011, 20:31
Forum: CB Radio Modifications
Topic: lincoln HR2510 MRF455 pcb
Replies: 3
Views: 8852

Re: lincoln HR2510 MRF455 pcb

I have just used some very short hookup wires to the main PCB after mounting the 455 on the rear panel, worked fine, I think I did rogerbirds mod from memory.
by The Defpom
Thursday 24th Nov 2011, 20:24
Forum: CB Antenna Systems
Topic: Made In the USA - SigmaIV ;)
Replies: 14
Views: 16875

Re: Made In the USA - SigmaIV ;)

This is a great post, thanks for sharing it.
by The Defpom
Thursday 24th Nov 2011, 20:14
Forum: Wanted !
Topic: Broken CB's wanted
Replies: 0
Views: 3677

Broken CB's wanted

I am always on the look out for parts radios, especially radios like the HR2510, Lincoln etc.

So if you have anything, please let me know what you have and what you want for it, international shipping may be feasible if it is a radio I particularly want to get for parts.
by The Defpom
Friday 18th Nov 2011, 7:01
Forum: CB Radio Repair and Troubleshooting
Topic: Deaf President George
Replies: 14
Views: 15876

Re: Deaf President George

I found a mistake on the PCB layout, there are two r27 on it, one below q8 and one just to the right of it, one of those will probably be r37, see which one connects to d22/r569 and then q18
by The Defpom
Thursday 17th Nov 2011, 22:15
Forum: CB Radio Repair and Troubleshooting
Topic: hr2510 president Lincoln CPU
Replies: 26
Views: 28269

Re: hr2510 president Lincoln CPU

I got a bunch of used mcu from the guy that was doing the chip switch installations in the USA, you might be able to get some from him, you need to specify the exact mcu number you want, as there are a few variants.

If only I could remember who it is...
by The Defpom
Thursday 17th Nov 2011, 10:46
Forum: CB Radio Repair and Troubleshooting
Topic: hr2510 president Lincoln CPU
Replies: 26
Views: 28269

Re: hr2510 president Lincoln CPU

Am finally home (for today anyway!) had any more progress with this radio ?
by The Defpom
Thursday 17th Nov 2011, 10:38
Forum: CB Radio Repair and Troubleshooting
Topic: Deaf President George
Replies: 14
Views: 15876

Re: Deaf President George

Thanks for the diagram, that was slightly better ! the resistor to lift is R37, not 57.
by The Defpom
Thursday 17th Nov 2011, 9:40
Forum: CB Radio Repair and Troubleshooting
Topic: Deaf President George
Replies: 14
Views: 15876

Re: Deaf President George

Unfortunately the circuit diagram I have for that radio is rubbish, I cannot make out most of the part numbers etc. But the first couple of things I would do is try removing the AGC function in case that is staying turned on, this can be done by lifting R37, Q18 is the AGC control transistor. The RF...
by The Defpom
Sunday 13th Nov 2011, 10:44
Forum: CB Radio Repair and Troubleshooting
Topic: hr2510 president Lincoln CPU
Replies: 26
Views: 28269

Re: hr2510 president Lincoln CPU

Replace it, as it effects the serial communications with other device such as display and plls, I have also come across issues with the factory glue causing shorts to the traces underneath them, so it might pay to clean original glue off, and replace it.
by The Defpom
Sunday 13th Nov 2011, 7:18
Forum: CB Radio Repair and Troubleshooting
Topic: hr2510 president Lincoln CPU
Replies: 26
Views: 28269

Re: hr2510 president Lincoln CPU

Pull and clean every plug on the mpu pcb, also pull the display pcb and resolder it all. Especially the through holes as I have seen those fail killing the display and confusing the mpu. If you have another radio you can pull the display pcb from it helps, as that can eliminate that as the problem. ...
by The Defpom
Sunday 12th Jun 2011, 23:04
Forum: General
Topic: No registration number
Replies: 1
Views: 5235

Re: No registration number

Sorry for the delay, I had been away, I cant process registrations until I get home to generate the serial number.

I emailed you your serial number a few minutes ago.
by The Defpom
Tuesday 22nd Mar 2011, 9:35
Forum: CB Radio Repair and Troubleshooting
Topic: cobra 29 dead
Replies: 7
Views: 8872

Re: cobra 29 dead

Can you please answer EACH of the questions I asked, I need to know the answers to all of them in order to be able to narrow down where the fault could be. On the back of the vol/on/off control there are two connections, usually a red wire and orange wire, you should have 13V on BOTH wires when the ...
by The Defpom
Monday 21st Mar 2011, 22:23
Forum: CB Radio Repair and Troubleshooting
Topic: President Lincoln control buttons not working
Replies: 9
Views: 13142

Re: President Lincoln control buttons not working

Glad to hear you got it sorted out. An easy way of getting the existing MPU IC out is to actually cut all the pins off the IC, and then desolder and remove them one by one, I found that to be one of the simplest ways of getting a faulty one out, and also helps avoid damaging the PCB traces from exce...
by The Defpom
Monday 21st Mar 2011, 22:13
Forum: CB Radio Repair and Troubleshooting
Topic: cobra 29 dead
Replies: 7
Views: 8872

Re: cobra 29 dead

Does the meter light up? Does the channel display light up? Has the inline fuse blown in its power cord? Have you checked for 13V at the on/off switch to confirm that power is getting to the radio itself ? Have you made sure it is not set to PA mode? You should be getting 5V at D19 with the radio tu...
by The Defpom
Wednesday 9th Mar 2011, 19:36
Forum: CB Radio Repair and Troubleshooting
Topic: President Lincoln control buttons not working
Replies: 9
Views: 13142

Re: President Lincoln control buttons not working

I should drop in here more often by the looks ! I wish I wasn't so busy with other things, anyway. One thing to try, as weird as it will sound, is swap out the LCD PCB, I have seen instances where a faulty LCD PCB has caused the MPU to appear to be faulty, it is a long shot, but an easy thing to rul...
by The Defpom
Thursday 9th Dec 2010, 22:14
Forum: CB Radio Repair and Troubleshooting
Topic: Cobra 2000 stuck in tx
Replies: 2
Views: 4450

Re: Cobra 2000 stuck in tx

Hi,
there are 3 possible causes, listed in likelyhood of failure.

C33 (10uF 16V), TR35 (2SC945), IC4 (MB3756)
by The Defpom
Thursday 9th Dec 2010, 7:46
Forum: Tips and forum usage
Topic: Picture Posting Problem?
Replies: 1
Views: 4275

Re: Picture Posting Problem?

The forum handles images differently, if it is a very large image the forum will link to it instead of displaying it on the page. There is also a button shown under the image name after you have "added" it to "place inline", if you want to have it display on the page then you nee...
by The Defpom
Thursday 9th Dec 2010, 7:30
Forum: CB Radio Repair and Troubleshooting
Topic: Emperor TS-5010 CPU Info
Replies: 1
Views: 4307

Re: Emperor TS-5010 CPU Info

The large IC is not the PLL, it is an MPU, which controls TWO PLL's, along with many of the radios functions, such as the display etc. There are differences between the MPU programs, and this includes the functions of its pinouts. Personally I would just keep the 2510 working, electronically they ar...
by The Defpom
Thursday 8th Jul 2010, 23:28
Forum: Wanted !
Topic: Christchurch NZ stuff wanted
Replies: 3
Views: 6924

Re: Christchurch NZ stuff wanted

I can do radio work via post if you cannot locate anyone down there that knows what they are doing, to be honest, I do not actually know of anyone else apart from me that works on AM/SSB CB's in NZ. As far as getting CB items in NZ, that can be hard, if I need anything I import it from the US or UK ...
by The Defpom
Monday 5th Jul 2010, 11:03
Forum: RadioMods Members Assistance
Topic: Different repeatershift on Kenwoord TM-741 ??
Replies: 1
Views: 3883

Re: Different repeatershift on Kenwoord TM-741 ??

HI,
Sorry, I know little about HAM equipment, all the ham information on the site is what I had collected from other sites and people over the years, I did not write those bits I'm afraid.
by The Defpom
Monday 5th Jul 2010, 1:57
Forum: CB Radio Repair and Troubleshooting
Topic: need help from the 148 gtl experts.???
Replies: 7
Views: 7896

Re: need help from the 148 gtl experts.???

That sounds fine at that point.
by The Defpom
Monday 5th Jul 2010, 0:18
Forum: CB Radio Repair and Troubleshooting
Topic: need help from the 148 gtl experts.???
Replies: 7
Views: 7896

Re: need help from the 148 gtl experts.???

Check the voltage drop across R111 (tell us the voltage on both sides of it, in TX and RX), I have come across issues on this and similar chassis where a capacitor is loading down the DC supply causing a large voltage drop across that resistor, it sounds similar.
by The Defpom
Sunday 4th Jul 2010, 22:38
Forum: CB Radio Modifications
Topic: converting Aussie to NZ am cbs, help please
Replies: 9
Views: 11276

Re: converting Aussie to NZ am cbs, help please

What I have done is move the 10.24MHz xtal to the PLL, break the tripled 5.12MHz output, add a crystal for NZ and then modify the oscillator to allow it to work 4MHz higher for the new crystal. the tricky bit is that sometimes this can load the oscillator when on SSB and the clarifier is turned full...
by The Defpom
Sunday 4th Jul 2010, 22:23
Forum: CB Radio Modifications
Topic: converting Aussie to NZ am cbs, help please
Replies: 9
Views: 11276

Re: converting Aussie to NZ am cbs, help please

I have converted AX144 for NZ channels before, it is a bit involved, but can be done by modifying the current circuitry's design and adding a few parts, realistically it can be tricky to get working properly sometimes, which can take a lot of time to convince it to work properly on all modes, as one...
by The Defpom
Wednesday 30th Jun 2010, 8:12
Forum: CB Radio Repair and Troubleshooting
Topic: Ham Jumbo MK1 - No Swing AM
Replies: 61
Views: 68744

Re: Ham Jumbo MK1 - No Swing AM

I would suggest upgrading the Zener, you can use any 10V Zener, but I suggest you get a 5W version, which is less likely to fail again.
by The Defpom
Tuesday 29th Jun 2010, 23:17
Forum: CB Radio Repair and Troubleshooting
Topic: Ham Jumbo MK1 - No Swing AM
Replies: 61
Views: 68744

Re: Ham Jumbo MK1 - No Swing AM

lbcomms posted whilst I was... Definitely worth checking the AVR to confirm it is operating correctly, I have replaced that circuit with a 7809 without any problems (I did add a 220uF 16V Electrolytic cap to it as well to ensure it had good smoothing, just a part I had a lot of, a smaller value woul...
by The Defpom
Tuesday 29th Jun 2010, 23:14
Forum: CB Radio Repair and Troubleshooting
Topic: Ham Jumbo MK1 - No Swing AM
Replies: 61
Views: 68744

Re: Ham Jumbo MK1 - No Swing AM

I am trying to see how pin 6 can be fed with 11V, as it passes through the band switch and returns to the VCO via the VR1/VR2 trimmers, so I am suspecting that there may be a short on the band switch wiring. (unless my diagram is a bit dodgy and is not showing a connection, which I suspect may be th...
by The Defpom
Tuesday 29th Jun 2010, 11:54
Forum: CB Radio Repair and Troubleshooting
Topic: Ham Jumbo MK1 - No Swing AM
Replies: 61
Views: 68744

Re: Ham Jumbo MK1 - No Swing AM

What are the voltages of all the pins on that IC (mid band ch 19).
by The Defpom
Tuesday 29th Jun 2010, 10:03
Forum: CB Radio Repair and Troubleshooting
Topic: Ham Jumbo MK1 - No Swing AM
Replies: 61
Views: 68744

Re: Ham Jumbo MK1 - No Swing AM

There is a Zener diode on that PCB, marked on the diagram as MZ205 (next to C5), it would pay to check that it is OK.
by The Defpom
Monday 28th Jun 2010, 12:09
Forum: CB Radio Modifications
Topic: Board in my old Courier Spartan PLL 40CH
Replies: 2
Views: 4547

Re: Board in my old Courier Spartan PLL 40CH

I think that I only have one set of diagrams for a spartan, I do not know if it is the same as yours, as they do not have the PCB number marked, but it is for a uPD858 PLL, so it may be the same one. According to the diagram AM power is VR6, so if that matches up then it will likely be the right dia...
by The Defpom
Saturday 19th Jun 2010, 11:38
Forum: CB Radio Repair and Troubleshooting
Topic: Ham Jumbo MK1 - No Swing AM
Replies: 61
Views: 68744

Re: Ham Jumbo MK1 - No Swing AM

Thank you very much Sue, that will definitely come in handy !
by The Defpom
Friday 18th Jun 2010, 8:35
Forum: CB Radio Modifications
Topic: Nato FM
Replies: 1
Views: 3472

Re: Nato FM

If you are meaning the Nato 2000 FM then that information is on the website:
http://www.radiomods.co.nz/pcma001salign.html
by The Defpom
Tuesday 15th Jun 2010, 8:21
Forum: CB Radio Repair and Troubleshooting
Topic: President lincoln display/audio fault
Replies: 26
Views: 27582

Re: President lincoln display/audio fault

Hi, What did you find to fix the display ? If there is no audio in all modes then it is something to do with the last signal or amp stages. If you have a RX signal with no audio then at a guess the squelch amp may be shorted out, check IC101 (NJM2902) on the main PCB slightly right of center towards...
by The Defpom
Sunday 13th Jun 2010, 20:23
Forum: CB Radio Repair and Troubleshooting
Topic: President lincoln display/audio fault
Replies: 26
Views: 27582

Re: President lincoln display/audio fault

The MPU PCB is a complex thing, without suitable test gear you stand no chance of locating the fault, at the very least you would need to determine what is working correctly on the PCB (if anything), you need to check the frequencies and control signals of the VCO's, and also the digital waveforms c...
by The Defpom
Sunday 13th Jun 2010, 10:25
Forum: CB Radio Modifications
Topic: K40 microphone
Replies: 7
Views: 11931

Re: K40 microphone

Hi, the upload limit for a post is set to 5MB, so you may be able to post it in another message, would be helpful for people to see it here.
by The Defpom
Sunday 13th Jun 2010, 0:11
Forum: CB Radio Repair and Troubleshooting
Topic: Replace MB8719 with MC145106
Replies: 4
Views: 8877

Re: Replace MB8719 with MC145106

I believe (although I have never tried) that you cannot replace an MB8719 with a MC145106, as they have a different PD output, one is reversed from the other.

You can replace the MB8719 with an RCI8719-99, which can be obtained from various places online.
by The Defpom
Monday 7th Jun 2010, 11:06
Forum: CB Radio Repair and Troubleshooting
Topic: Ham Jumbo MK1 - No Swing AM
Replies: 61
Views: 68744

Re: Ham Jumbo MK1 - No Swing AM

The Cybernet chassis (which the Jumbo is) is known for having poor AM power, I have come across many radios that could not do 4W on AM because of the audio problem, in reality your probably best to just set the AM power at 2.5-3W so that you have some swing on AM, if you need more power just drop a ...
by The Defpom
Sunday 6th Jun 2010, 11:34
Forum: CB Radio Repair and Troubleshooting
Topic: HMV Roadhound TX77 Repair
Replies: 3
Views: 5361

Re: HMV Roadhound TX77 Repair

Check TP1 first, if the voltage is at one extreme (close to 0V or 5V) all of the time then the PLL is trying to compensate for the frequency being incorrect, if the voltage is 0V the first thing you should do it try replacing C3, C4 and C5 (they smooth out the voltage feeding the VCO), if one has sh...
by The Defpom
Sunday 6th Jun 2010, 11:13
Forum: CB Radio Repair and Troubleshooting
Topic: Cobra 25ltd st
Replies: 2
Views: 4502

Re: Cobra 25ltd st

L20 is the 54MHz filter, it is tuned to limit RF output on 54MHz (1st harmonic), you need a spectrum analyser to adjust it properly.

Your probably best to just adjust it back to about 3/4 (towards the top), that should at least be approximately correct, certainly closer than where it is now.