Search found 432 matches

by The Defpom
Thursday 9th Dec 2010, 22:14
Forum: CB Radio Repair and Troubleshooting
Topic: Cobra 2000 stuck in tx
Replies: 2
Views: 2121

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: 2254

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 need to click on that t...
by The Defpom
Thursday 9th Dec 2010, 7:30
Forum: CB Radio Repair and Troubleshooting
Topic: Emperor TS-5010 CPU Info
Replies: 1
Views: 2311

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: 3559

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: 1707

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: 3325

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: 3325

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: 5415

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: 5415

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: 37783

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: 37783

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: 37783

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: 37783

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: 37783

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: 2233

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: 37783

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: 1592

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: 13548

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: 13548

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: 6420

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: 4683

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: 37783

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: 2607

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: 2215

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.
by The Defpom
Sunday 6th Jun 2010, 11:01
Forum: CB Radio Repair and Troubleshooting
Topic: Ham Jumbo Alignment Problem
Replies: 4
Views: 5786

Re: Ham Jumbo Alignment Problem

If it were me, I would undo everything and return it to original first (apart from the EPROM board), and then go from there, possibly re-modding anything that is needed.

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