Cobra 139xlr

[dxing.bruce]

Hey: Gang.

I'm really stuped with this Cobra 139xlr I'm working on.

I recapped the entire radio including the tantalum & electrolytic capacitors. I also replaced the four 2sc1419 regulators with new ones.
The radio will only put out 1 w on AM & 3 w on SSB.

I replaced the 2sc1306 driver & 2sc1307 final with new old stock ones I had, same issue still.

I even replaced the pre driver 2sc1973, issue still exists.

I even installed a new relay, did not solve the issue.

I even replaced the two bias diodes that attach to the driver & final, did not help.

I'm totally stumped.

Any suggestions guys as I'm pulling my hair out with this radio.

Thanks in advance.

 

[brandon7861]

Check out technical bulletin 1209B

 

[dxing.bruce]

Check out technical bulletin 1209B

Did all listed in the tech updates, no difference. 1w on AM & 3w on SSB.

 

[nomadradio]

How much power did you get before the overhaul?

73

 

[dxing.bruce]

How much power did you get before the overhaul?

73

Same power before & after all electrolytic caps, now driver & new final, plus new relay. Turns out someone had their golden screwdriver inside & mistuned the tx rf variable inductors before the pre driver stage. Got it back to 4 / 12 watts now. Thanks to everyone for their time & input.

 

[nomadradio]

Rock on! Good to hear it was a routine issue. Tweakeritis is always a possibility until you rule it out.

73