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  1. slingslingbinks

    Cobra 2000 no modulation.

    What's everyone think of to use this as a replacement for VR12? This one????? https://www.mouser.com/ProductDetail/Amphenol-Piher/PT10LV10-501A2020-S?qs=pCZPOPZMYPh0kKMSfZYsdg%3D%3D Or this one...
  2. slingslingbinks

    Cobra 2000 no modulation.

    I haven't tested it yet or started the alignment
  3. slingslingbinks

    Cobra 2000 no modulation.

    SO Just to report (As many times it doesn't) I found TR12 to be at fault, I will now perform the alignment and do further over the air testing before returning the radio to the customer. Thank's everyone for your help and i hope if someone else has this problem, going through these 5 pages, it...
  4. slingslingbinks

    Cobra 2000 no modulation.

    Hey Brandon, You are DA MAN. I pulled out VR12 and ohm check it and it's fubar, I don't see that part number anywhere on the WWW, I have a donar part's cobra 138XLR and stole all the VR style semi fixed resistor's out and found one marked around 500, Installed it and BAM I have transmit audio...
  5. slingslingbinks

    Cobra 2000 no modulation.

    Hey Brandon, Look's like it's time to get on the hunt for a replacement VR12. It still has me wondering. If VR12 is fubar (and it appears it is) Will this also affect SSB? Mabey i need to check everything around TR34 as well and VR11.
  6. slingslingbinks

    Cobra 2000 no modulation.

    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.
  7. slingslingbinks

    Cobra 2000 no modulation.

    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...
  8. slingslingbinks

    Cobra 2000 no modulation.

    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...
  9. slingslingbinks

    Cobra 2000 no modulation.

    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
  10. slingslingbinks

    Cobra 2000 no modulation.

    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.
  11. slingslingbinks

    Cobra 2000 no modulation.

    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...
  12. slingslingbinks

    Cobra 2000 no modulation.

    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.
  13. slingslingbinks

    Cobra 2000 no modulation.

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

    Cobra 2000 no modulation.

    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...
  15. slingslingbinks

    Cobra 2000 no modulation.

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

    Cobra 2000 no 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
  17. slingslingbinks

    Cobra 2000 no modulation.

    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...
  18. slingslingbinks

    Cobra 2000 no modulation.

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

    Cobra 2000 no modulation.

    No Transmit modulation on Am, SSB Or PA