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. Maybe be the mode switch after all? At TR41 and both test posts i could adjust the voltage at the outer leg of 41 while transmitting on AM by adjusting vr10 and get a volt reading from less than 1 volt up to about 7 but then sometimes it will show 13 volts at that leg and I can’t adjust it at...

thanks Nomad. I checked the 2 bias posts. Same full voltage as at the front lead of TR41. When you key radio it drops to 6.2 at TR41 and at the two bias posts but still no power out. So not the mode selector likely? What is it then?? Mystery. voltage at driver: ground, 290 millivolts (AM...

So This kind of complicates the troubleshot because I previously checked Q401 and it checked out ok so don’t think it’s that and Those 3 resistors are stock original values so do t think it’s that. Didn’t touch those 2 smaller transistors. Like I said I ordered new zener. I had an extra...

so you think TR41 is ok then? Nomad was saying that front leg should be about 6.8 volts which is what the schematic says too. Full voltage seemed to much? But I suppose that could be ok because if you’re saying TR41 goes dead for SSB and there’s no output on SSB either, then likely the problem...

Found on eBay. Dreading that job trying to get that all apart and then desolder all those tiny solder points. Oh well. Thanks!

Is there a way to actually repair the channel selector segments that are out on the cobra 2000 channel selector LEDs? I have a couple out but it is basically impossible now to find OEM replacements for them and I don’t know if there is some “equivalent” you can buy to replace them. Any advice...

Interesting looks like some work was done in this power supply. C302 has been replaced by a 220 UF and C410 is a 6800. Are those ok? I actually read somewhere about increasing C410 even more. or should I put them back to stock sizes?

I am getting basically full power (13.8) out of the front and center legs of TR41. Normal (about 7 volts) out of the rear leg. But this is the AM regulator. So would that affect SSB too? There is no power out on SSB either. Just trying to understand. But either way I assume this need to be...

Yes sorry wrong identification. Center lead. Getting inconsistent voltage readings at both. Are voltage readings at these 2 the simplest way to know if they are good or not? I will check TR41.

For now I am running off my dc power supply. So I think I have found the issue with wattage fading as the radio stays keyed up. The final starts out fine voltage wise but quickly fades down to basically zero. The driver seems to stay ok. so I replaced the final. I’m not getting anything at...

Ok located the issue of only 6.8v at IC4 and elsewhere. All set. Now will investigate higher voltage on the power supply side.

yes thanks. I know how to check those 2 biases. The driver one was waaaay to high though I don’t know why because I didn’t touch it. The final bias was ok. The max wattage a can get on a dead key is 3 through vr10. And I peaked all the other coils. .There something keeping the power low. I...

I replaced those 2 from an old Cobra 140 I’ve been using for parts so they are exact replacements. No change. Wattage drops within seconds after keying the mike and the bias currents are very low.

I never touched those so I assume they are in correctly. Whether they are bad or not I’m not sure. Would that cause the symptom I described above where the TX power starts off “ok” and then within several seconds fades down to less then 1 watt and little driver or final bias readings? Just...

Ok here is an update and more information. I thought I had added onto the original post but I guess I didn’t save it. I went downstairs this morning and now it turned on. Found a bad solder spot in the bridge rectifier that was causing the short and not to turn on. Voltage on the board seems...

Before it died, I noticed the wattage would start at 3 or 4 then drop down to under 1 while the radio was keyed. I could not turn up the watts through VR10.

Ok I’ll check it out. The fuse is not blown. I will check it on DC only tomorrow. I actually did check the final bias right before it died and it was only a few milliamperes as I recall. When it should be 50 I believe. I do have decent multimeter.

I have very little Tx. I replaced the driver and final thinking one was bad but still nothing. I’ll get a few watts out of it and then it drops off while you are keyed. And the SWR seems to be jumping around as well. I cannot peak the tX more than a couple of watts max. And I have a really...

I had very little Tx. I replaced the driver and final thinking one was bad but still no improvement. . I was getting a few watts out of it and then it would drop off whilekeyed. And the SWR seems to be jumping around as well. I couldn’t peak the tX more than a couple of watts max. There was...