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Hey Bob. I put a 1N4148 in the D64 spot and at C of TR26 i have,,, 4.362 VDC AM RX. 4.535 VDC SSB RX 1.825 VDC AM TX 4.535 VDC SSB TX That is when the mic audio is not working and Failing. You didn't say what mode to check C of TR26, so i did them all.

Hey Bob. I need to put a diode in D64 location before i can test this. I don't have the 1S1588 Diode and it's questionable if the D64 diode was correct and i can't read it. NTE say's the 1S1588 interchanges to the NTE519, as well 1N914 and 1N4148 interchange to NTE 519 and i stock the 1N914 and...

I pulled D64, Unable to read what it say's on it, Tested as a diode. uf - 701MV C 4pf Multimeter set in Diode mode and with the + lead on anode side and - on cathode side it read's .586. Reverse lead's and it say's .of Tested the radio with D64 removed No Transmit Modulation anywhere, I did...

OK Brandon, I'll pull D64. In the mean time i redid my original; picture in Message 33. All reading's are in SSB RX

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.

Touching each end of the diode, and the ground of the voltmeter to the wire soldered between the xtal's.

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...

D64 has voltage going through it, But when i turn VR12, There's no change in the voltage

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...

There should be 5.7VDC to B of TR25, Checking foil side now.

No Transmit modulation on Am, SSB Or PA

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...