<![CDATA[Worldwide DX Amateur Radio Forums - Ham - CB - HF - VHF - UHF - Tech, & Repair]]> http://www.worldwidedx.com/ en Fri, 20 Nov 2009 22:09:11 GMT vBulletin 60 http://www.worldwidedx.com/images/misc/rss.jpg <![CDATA[Worldwide DX Amateur Radio Forums - Ham - CB - HF - VHF - UHF - Tech, & Repair]]> http://www.worldwidedx.com/ Swapping out Chan LEDS. http://www.worldwidedx.com/tech-repair/37172-swapping-out-chan-leds.html Wed, 18 Nov 2009 20:47:45 GMT Are these easy to swap out and are all CHAN LED have the same contact point or legs. I have a green Chan LED from a realistic radio Im wanting to... Are these easy to swap out and are all CHAN LED have the same contact point or legs. I have a green Chan LED from a realistic radio Im wanting to replace onto my pres.grant. one LED is out. ]]> 15minigrass http://www.worldwidedx.com/tech-repair/37172-swapping-out-chan-leds.html Galaxy Starlight Display Whine http://www.worldwidedx.com/tech-repair/37170-galaxy-starlight-display-whine.html Wed, 18 Nov 2009 18:07:16 GMT The friends are keeping me busy lookin' for fixes for 'em.....ah that's what friends are for :thumbup:

Has Galaxy DX 98VHP with Starlight Display. Has developed like a 100hz tone in it that is air-audible on his end and it comes through on transmit. Face lights are on a dimmer and the tone reduces and goes away as the dimmer is turned down and then off....but he's gotta have front panel illumination ya know. So anyone know of a fix for this whine-tone coming off the Starlight display?

As always....indebted for any help!! :thumbup1:

]]> Wire Weasel http://www.worldwidedx.com/tech-repair/37170-galaxy-starlight-display-whine.html Cobra 2000 gtl reads 92.0000 http://www.worldwidedx.com/tech-repair/37105-cobra-2000-gtl-reads-92-0000-a.html Fri, 13 Nov 2009 23:23:29 GMT I bought a cobra 2000 the other day, hooked it up and it reads 92.0000 on every channel??? Anyone know what this is about? Also, it doesnt receive or... I bought a cobra 2000 the other day, hooked it up and it reads 92.0000 on every channel??? Anyone know what this is about? Also, it doesnt receive or TX from channels 2-8. Thanks!! ]]> jerzeyj420 http://www.worldwidedx.com/tech-repair/37105-cobra-2000-gtl-reads-92-0000-a.html Besy Way To Desolder Amp Board Tabs http://www.worldwidedx.com/tech-repair/37019-besy-way-desolder-amp-board-tabs.html Sun, 08 Nov 2009 20:51:02 GMT A friend of mine is going to be bringing me a Palomar Blue 225 like the pic. Has lost about 25 watts of power but still working. Looked inside and... A friend of mine is going to be bringing me a Palomar Blue 225 like the pic. Has lost about 25 watts of power but still working. Looked inside and says there are two diodes that have popped loose presumably due to heat ( I told the boy to mount a fan on de thing). Says diodes have popped loose from the solder side of the board and the board will have to be unmounted from the overall unit. Says there are large solder tabs in the corners presumably connecting the board ground to the case. I can check/replace/resolder the diodes for him but have no experience desoldering the large corner solder blobs from an amp case.

What's the best-easiest way to do this? I have a large soldering gun and small butane hand torch and pretty good soldering skills.

Thanks for any tips!
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]]> Wire Weasel http://www.worldwidedx.com/tech-repair/37019-besy-way-desolder-amp-board-tabs.html A-Static Mobile Max (v3.2) no power when keying up http://www.worldwidedx.com/tech-repair/36999-static-mobile-max-v3-2-no-power-when-keying-up.html Sat, 07 Nov 2009 06:22:16 GMT I have a a-static mobilemax, it's v3.2 with the 28 seconds of audio recording and 1 roger beep. When i key up with it powered up, the metere doesn't move, and there's no audio coming from the unit. if the power to the unit is off, the radio works fine. I tested it on a cobra 29 NW LTD & my galaxy 949, and it fails to work on either unit. The unit it setup to work with a 4pin cobra mic.


Has anyone ever encountered this before? :headbang ]]> BigJeff http://www.worldwidedx.com/tech-repair/36999-static-mobile-max-v3-2-no-power-when-keying-up.html Protection diode on rci 2950 http://www.worldwidedx.com/tech-repair/36984-protection-diode-rci-2950-a.html Fri, 06 Nov 2009 08:44:45 GMT So tonight I got in a hurry to try out a new power supply and hooked up the radio backwards, now it doesn't work... at all....

Figured I probably blew the protection diode but I cannot find information on which one it is. I see three black diodes with silver bands in the back corner by the power leads, could all three of them be protection diodes?

If anyone could give me a board number to identify the right one it would be appreciated, as I would rather own a $200 radio and not a $200 boat anchor. ]]> kd8hjr http://www.worldwidedx.com/tech-repair/36984-protection-diode-rci-2950-a.html 90 DAY WONDERS ?? http://www.worldwidedx.com/tech-repair/36982-90-day-wonders.html Fri, 06 Nov 2009 03:25:05 GMT I have a question. Are the thick white plastic/ceramic insulators used in most new radios for the driver/final/modulator transistors as good as Mica... I have a question. Are the thick white plastic/ceramic insulators used in most new radios for the driver/final/modulator transistors as good as Mica insulators ??? I have heard the white insulators referred to as "90 day wonders" by several GOOD techs. But... I have also heard some good techs defend them and say they are better than mica. What are they made of???Plastic?? ceramic?? or what ?? I have an RCI2950 that has the white insulators, and I just added a speech processor to the unit. The driver and finals will be modulated a LOT harder now, and I need to know if changing the insulators will help the reliability. What experience have you guys had with this. Thanks.

- 399 ]]> unit_399 http://www.worldwidedx.com/tech-repair/36982-90-day-wonders.html 4 OHM EX-SPEAKER ON MY CB http://www.worldwidedx.com/tech-repair/36957-4-ohm-ex-speaker-my-citizens-band-radio.html Wed, 04 Nov 2009 18:12:30 GMT Will running a 4 ohm external speaker (kenwood kes-5) on my uniden grant cb hurt the radio.? isnt most external cb speakers 8 ohm.? i usually use the... Will running a 4 ohm external speaker (kenwood kes-5) on my uniden grant cb hurt the radio.? isnt most external cb speakers 8 ohm.? i usually use the texas ranger external speakers and they sound good. but truthfully the kenwood kes-5 millitary grade external speaker sounds better. just not wanting to harm my radio. ]]> 190 http://www.worldwidedx.com/tech-repair/36957-4-ohm-ex-speaker-my-citizens-band-radio.html Astatic 600/Paradynamics rotary switch? http://www.worldwidedx.com/tech-repair/36949-astatic-600-paradynamics-rotary-switch.html Wed, 04 Nov 2009 00:48:00 GMT Hi everyone, I have an Astatic 600/Paradynamics 3 movement swr/mod/wattmeter. The 4 position switch to change wattage has sheared off flush with... Hi everyone, I have an Astatic 600/Paradynamics 3 movement swr/mod/wattmeter.

The 4 position switch to change wattage has sheared off flush with outside of the enclosure.

Has anyone changed one of these before?

I am needing a part number and a source.

Thank you for any help you can offer. ]]> d1g1man http://www.worldwidedx.com/tech-repair/36949-astatic-600-paradynamics-rotary-switch.html VSWR at DC http://www.worldwidedx.com/tech-repair/36948-vswr-dc.html Tue, 03 Nov 2009 22:46:58 GMT Does VSWR have any relevance at DC? Does VSWR have any relevance at DC? ]]> C2 http://www.worldwidedx.com/tech-repair/36948-vswr-dc.html Help! Uniden Washington Channel Mod http://www.worldwidedx.com/tech-repair/36937-help-uniden-washington-channel-mod.html Tue, 03 Nov 2009 18:15:40 GMT Hi there everyone! I am attempting to put channels in a buddies rig and I am having an odd problem, I would sure appreciate your input. It is a... Hi there everyone! I am attempting to put channels in a buddies rig and I am having an odd problem, I would sure appreciate your input.

It is a Uniden Washington, MB8719 3 Button Board number PC-385AH.

The one that I have attempted is the method where you isolate pin 10, and connect one wire to pin 10 then the other to ground (SPST).
Also, another SPST to connect pins 11 and 12 (Pins Not Isolated).

I get a lower frequency jump when 11 and 12 are connected, but when I switch pin 10 to ground it just goes lower.

In other words, I can't get any high channels out of it.

I would love to put an EXPO B kit in it, but no-one seems to have one.

I would just do "the_mod" but this rig is not quite in good enough shape for that investment.

I have played with the VCO, and it locks ok but I feel like I am missing something or doing something wrong.

Perhaps if someone has this same rig with the PLL jumped, they might be able to Eyeball it and see how theirs was done.

Thanks again! ]]> d1g1man http://www.worldwidedx.com/tech-repair/36937-help-uniden-washington-channel-mod.html cobra 29 with mosfet final http://www.worldwidedx.com/tech-repair/36931-cobra-29-mosfet-final.html Tue, 03 Nov 2009 04:13:25 GMT Did a mosfet change and followed instructions from cbtricks. Here is the problem R40 burned up so i replaced it with a new resistor (bigger) 1 watt... Did a mosfet change and followed instructions from cbtricks. Here is the problem R40 burned up so i replaced it with a new resistor (bigger) 1 watt and also replaced c20 cap next to it. Worked great then R40 gets hot and burns up again??? Need help Thanks. ]]> Number15 http://www.worldwidedx.com/tech-repair/36931-cobra-29-mosfet-final.html HR 2510 NO TX WATTAGE http://www.worldwidedx.com/tech-repair/36858-hr-2510-no-transmit-wattage.html Thu, 29 Oct 2009 23:03:43 GMT Hr2510 rx good but has no tx power shows about a half watt on AM if I keep the mic keyed that half watt goes to 0 watts in a couple of seconds ,I... Hr2510 rx good but has no tx power shows about a half watt on AM if I keep the mic keyed that half watt goes to 0 watts in a couple of seconds ,I have already replaced the final mrf497,the driver 2sc2166 also Q124 audio driver Q134 pre driver ,changed C95 and C97 and C75 ,all voltages on ic104 are correct,checked voltage on Q125,Q126 and Q136 all check out according to service manual now I am stumped any help would be great ]]> CBC544 http://www.worldwidedx.com/tech-repair/36858-hr-2510-no-transmit-wattage.html help with cobra 29 ltd classic http://www.worldwidedx.com/tech-repair/36822-help-cobra-29-ltd-classic.html Wed, 28 Oct 2009 06:30:09 GMT HI i have 1 for you tech i have a cobr 29 ltd classic side mic it was working just fine tuned up with a 5 watt DK swing to almoast 15 watts yest the... HI i have 1 for you tech i have a cobr 29 ltd classic side mic it was working just fine tuned up with a 5 watt DK swing to almoast 15 watts yest the radio was also cliped that is all my buddy used it in his big truck a month or so now ti keys up and swing the same but audio is real low and nothing comes from the speaker no speaker is good as wen i try the pa i git audio from cb channel and also my voice thru pa dont know if this is right the only way i can git audio from speaker si to ground ext sp to chassie of radio but then audio is good for 5 feet but after that it dies off also this gives me talkback that souns good stil a good out put dont know what my problem might be i dont think it is audio ic help ]]> cottentop http://www.worldwidedx.com/tech-repair/36822-help-cobra-29-ltd-classic.html So you want to learn more about radio repair http://www.worldwidedx.com/tech-repair/36798-so-you-want-learn-more-about-radio-repair.html Mon, 26 Oct 2009 00:56:06 GMT *Please ask questions by replying to the thread not with PMs. That way everyone gets questions answered and every one else gets to learn more.* ... Please ask questions by replying to the thread not with PMs. That way everyone gets questions answered and every one else gets to learn more.

Scope
  • General
  • Shop equipment
  • homebrew test equipment
  • Receiver
  • Transmiter




Years ago I started off in electronics with nothing more that a volt meter. Analog at that. I now have a well stock repair shop going with some decent equipment. But took years to accumulate. Back then there was no internet to look stuff up on. No great forums like this one to go on and ask how something works, or where to find a part. Well, at least there were local places to find parts! Everything was trial and error. At least for me.

What I am hoping to do in this thread is share with you some of the tricks of radio repair. And maybe some of the other techs will jump in and add a few things. Reason I am doing this is that I get pm's and emails from cb'rs and new hams everyday asking different things about their radios. Just today I received one from the Netherlands asking about an article I wrote a few years ago on another forum.
Also by reading the forums there are many folks that are trying to repair their own radios. These are the different folks than just the ones that want plug and play. So don't worry shop owners. You loose no business with this. The plug and play operators will continue to support you :)

The art of radio repair is dying. Around my area there is only one other person that works on older tube stuff. And he is semi retired. There are three other shops that only repair solid state units. If you want to start off repairing your own rigs there is nothing better to start with than a CB Radio. Why?? Well it does not matter if you are a cb or ham radio operator. You have to start somewhere. CB's are cheap. You can pick them up at yard sales for a couple of bucks. So if you destroy it you are not out much and maybe a lesson learned.

Standard Shop Equipment
Here is some of the tools you will need to start repairing radios.
A good set of hand tools.
Regulated power supply.
Dummy load. (A home-brew 100 watt is fine)
Analog and digital volt meter.
25 to 45 watt soldering irons.
Solder wick
Solder sucker (Radio shack has a nice solder sucker iron. Get them while they last)
Assortment of test clips
Magnifying lamp (Well I need one)
Frequency counter

I want but can not afford shop equipment
Service Monitor
Dual trace oscilloscope
Transistor tester
Capacitor tester
Variable bench power supply
Signal tracer


The bottom list gets very expensive but are a must for professional repairs. But if you are affected by today's economy, you probably will struggle to get the stuff. And no need to take food out of the families mouth just for you to learn. So lets see if we can compromise a bit.

Service Monitor.
This is the next best thing since sliced bread. If you look around the net you can pick one up for a few hundred dollars. But the good ones are more like a few thousand bucks. I use the IRF 1200. And see them all the time for 3 to 4 grand. Take a look. You will see. But since we are starting off with cb, I will show you away you can test a radio.

The Poor Mans Service Monitor / Generator (P.M.M for short)

The poor mans monitor is nothing more than a converted cb radio. The first service monitor I ever owned was a modified cobra 23 channel radio. The radio was removed from its shell and mounted in a larger metal case. This way I could add the needed components to complete the unit.

I added a internal power supply. This does not have to be a large amp supply but needs to be stable. The driver and final of the radio will be removed. The pre-driver will deliver all the power you need to test receivers with. You will need to build an attenuator so you can vary the output in generate mode. In the one I had I used a 12 position switch with resistors added of various resistance to achieve less db output.

With today's export rigs, you can build one that will cover more frequencies and AM, CW, SSB, FM.

List of things to add to monitor
  • Internal power supply
  • Dummy Load
  • RF attenuator
  • Tone generator
  • Frequency off % meter
  • Frequency counter
  • On Air pick up loop

Some radio's of choice are the Cobra 25 GTL or Cobra 29 GTL (Classic). The older model. These were built tough and hold up good. So if you have an old beat up one lying around use it. One important thing to consider is you need to add some shielding to certain area’s. If you can find some very thin sheet metal you can solder it together. Double sided pc board works great also. Most of the shielded compartments will be small so it will not take much. There are several sources for this including RF Parts and Tesco.

We will start looking at the radio antenna lead. We will need to isolate the area were the TX and RX comes together at. You will need locate D8 and R39, L10, C44, and C142.

More to come ]]> Radio Tech http://www.worldwidedx.com/tech-repair/36798-so-you-want-learn-more-about-radio-repair.html