have a cobra 2000 with no power at tp7 or tp8... if I run a jumper wire and power tp7 I get a 5 watt carrier?? No audio though radio is Direct Injected. Any input would be great...
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Cobra 2000 no transmit power no power at TP7
- Thread starter Justwantdahifiaudio
- Start date
Been playing around with am regulator voltages don’t seem right 13.8 13.8 and 8ish volts... but only get carrier when jumper is ran from 13 volt off radio.. soI’m missing something and volatge to the test points for biasing isn’t there
Update I got the radio cheap because it was broken, was talking to the guy who owned it and said this all happen from adjusting the bias he dropped a test lead and short something out... hint the wire I found running from the am regulator to tp7 but that doesn’t fix It cause there isn’t audio..
your AM regulator transistor (TR41) is shorted.
if your measured 8ish volts was on the emitter leg (closest leg to the front of the radio) then you would have a very high deadkey on AM but no audio.
since you are saying that you are not getting that 8 volts at TP7 and 8, then the path goes from the emitter of TR41, through the mode switch, right to TP7 and 8, which means that there is something up with the mode switch.
my guess is that SSB works just fine.
If it does,then the break would be between the emitter of TR41 and the mode switch.
if it does not, then the break is between the mode switch and TP7 and 8.
it would of course be easier to diagnose if the radio was in front of me.
LC
if your measured 8ish volts was on the emitter leg (closest leg to the front of the radio) then you would have a very high deadkey on AM but no audio.
since you are saying that you are not getting that 8 volts at TP7 and 8, then the path goes from the emitter of TR41, through the mode switch, right to TP7 and 8, which means that there is something up with the mode switch.
my guess is that SSB works just fine.
If it does,then the break would be between the emitter of TR41 and the mode switch.
if it does not, then the break is between the mode switch and TP7 and 8.
it would of course be easier to diagnose if the radio was in front of me.
LC
Ok so I did find a bad switch!!!!! I got power to my test port but Looks like my volatge is crazy 13.8 on rx and 3.1 volts on tx I can hear a little bit of audio.. my voltages are not right at tr41 not even on rx so next looks like tr41?
One other thing if I just want to jumper the switch for AM, is it just hook orange and red wire together? Radio is injected so ssb isnt a opinion anyways....
Another update got the radio working, I can only get audio using the stock mic??? When I inject through c174 + side I lose all rf power??? Everything is working rádio is putting out good numbers and sounds good with a stock mic... sorry if I’m boring but you guys have been a big help
Never mind forgot the blocking cap because I removed the switch for stock mic to direct injection... thanks for all the help