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Hey Bob.
With eather TR24 or TR25 removed i DO have transmit modulation in AM, SSB and PA.
With TR26 Removed i only have transmit modulation in SSB, No Transmit modulation in AM and PA is choppy out the speaker and no voice out the speaker.
Hey Brandon.
I installed a new 1.5K resistor in R165,
Checked voltages across D64.
In SSB the Anode side has 5.156 VDC and Cathode side has 4.884 VDC
At the Cathode of D64 with VR12 Full CW the voltage is 4..888 VDC and with VR12 Full CCW the voltage is 4.743 VDC.
The Voltages at the Base of...
Hey Brandon,
You said------ You need to lift a leg and test the Vf of the diode out of circuit.
With my gorilla finger's it would be easer for me to pull the diode and test it and if good or bad, Replace it with new since the lead's will be longer, But i'll pull it and test it in the am.
Hey Frankenstein.
Ohm checked R165 in circuit and it was 11M, Pulled it and out of circuit it measured 1.48K. In speck if it's a 10% resistor at 1,500 ohm's for R165,
Just for giggles i tried the radio with out R165, Still no AM transmit modulation, But SSB transit's and has transmit modulation...
Hey Xracerx, Yes TR24 is in the correct way.
I pulled the new TR24 and 25 and reinstalled the original ones.
Still no Transmit modulation,
For what it's worth, I pulled TR26, Tested ok and it DOES have transmit modulation in AM, SSB and PA with TR26 Removed,
So in my eye's it's going down this path
Exactly, What's what i posted in message #34.
So i pulled TR24, I drew a pic of the way it was in the board not completely sure what it looked like under the transistor and found the picture on the board different than what i drew, I tested the radio WITHOUT TR24 in it and AM, SSB and PA now...
Morning Mr. Nomad
Cobra 2000,
Transmits carrier on AM.
Receives tone on AM and SSB.
No modulation on AM, SSB or PA
You remember that white Hygain radio you sold on e-bay? I was the buyer.
Cheer's Scott Colorado
All electrolytic cap's replaced, Still no transmit modulation, I shot gunned a new TA7222O (IC6) in still inop.
I found a part's list in CB tricks https://cbtricks.org/radios/cobra/2000gtl/graphics/cobra_2000gtl_om_part_list.pdf And there are Tantalum cap's listed that i didn't see listed as...
Thank's Handy.
I took a break from the 2000 to recap my heathkit T-4 audio tracer and made up new lead's. Just so i can trace the audio path, Now when i test the audio path with the signal tracer, all is good and i hear my voice up to where the audio path goes into the board when i key the mike...
Thanks Handy Andy. I'm currently making a list to recap this radio and in the mean time I'm back to a tram D-201A tube socket replacement. As soon as i get the 2000 back on the bench, I'll get to checking out your suggestions
Further ohm testing the pin's 1 and 2 of the mike socket, something just didn't jive. I have a Cobra 138XLR in my collection and pulled the bottom cover and compared it to this 2000, The 138 has the shield going to the ccw terminal, Audio from the mike going to the center and the center...
Hey X Racer.
No AM modulation, It has AM dead key watt's on watt meter, it's on frequency when monitoring through a freq counter, No SSB transmit (Since no modulation) and nothing going pot the pa jack to a speaker while in PA mode.
No movement on the modulation meter, Mic work's on the mic...
3 year old post and i have no modulation in am, ssb or out the pa speaker in pa mode as well
A question for Hand Andy, When you ohm test from pin 1 and pin 2 at the mic connector and the ohm's don't change form 1,038 ohm's no mater where the Dyna mike control is turned to. I never red what to do...
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