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Lralph
Posted on Monday, May 19, 2003 - 9:33 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

I have a Cobra 2000 that looks like it did the day it came out of the box back in '95 or around then. It developed a problem in the transmit side and would not transmit. I took it to a shop here in San Diego to have it repaired and they had it in their posession for a few months "trying to fix it". They're excuse for the long period of time was they were really busy. I was finally told that they couldn't fix it and I could pick it up. Well when I picked it up not only did it not transmit but the receive side now does nothing but squeal. Obviously I took it to the wrong place, my only concern is what did they do to it while they had it! I have since set up with a new rig and was wondering if it' worth it to have it fixed by someone reputable. Oh by the way, the shop has since gone out of business, imagine that. How much is one worth in the condition that it's in? I probably wouldn't use it anymore anyway.
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307
Posted on Tuesday, May 20, 2003 - 6:57 am:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

Worth??? About $400 if mint and has the speaker...

Fix???? I will be happy to repair it for you if you email me at tech307@copperelectronics.com

307
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Viking
Posted on Tuesday, May 20, 2003 - 2:13 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

Get it fixed and keep it. You won't regret it.
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2600
Posted on Tuesday, May 20, 2003 - 5:46 pm:   Edit Post Delete Post    Move Post (Moderator/Admin Only)

Umm, does it say "Made in Taiwan" on the serial number sticker? There's nothing wrong with the quality of a Taiwan 2000GTL, but it dates the thing, since they moved production from Taiwan to the Philippines in the late 80's. There are a handful of small electrolytic capacitors in this radio rated at 10 Volts. All of them are used in circuits with less than 10 Volts on them, but this type of part tends to fail from age first. There's one that will kill the receiver audio, but the receiver meter will still kick around on channel noise. That one won't affect transmit audio. There's another that will burn out the speaker coil when it shorts. Another one that shuts down ALL transmit power, so much that a nearby radio won't hear a peep leaking out of the 2000 when you key it. Another one will kill the final's bias current, reducing power and making SSB transmit scratchy.

If the shop you went to was baffled, I would suggest looking at C95, a 47 uF 10Volt radial capacitor. It's located at the rear end of IC3, the balanced modulator chip. IC3 is about two inches to the rear of the front edge of the circuit board, just about centered left-to-right. If you unsolder one leg of C95, or just remove it completely the transmit power will return if that was the problem. Don't just leave C95 out if this fixes it. The part is there to filter noises that could leak into the transmitter from the power supply.

If that's not it, you didn't waste a lot to find out.

73

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