Cobra 29ltd no transmit 35-40

[Capybara]

I've had 2 or 3 where the VCO voltage would become "jagged" on the scope at the extremes, not allowing lock on either the top or bottom 5 or 10 frequencies.
The issue remained after a recap, but was resolved with a "shotgun" style solder reflow in the area near the mixer/ varactors.... Sometimes it's just goofy stuff with what seems like no rhyme or reason.

 

[Night Stalker10]

This is where a 'scope pays for itself. Watching the tuning voltage while you flip from channel 1 to 40 and back lets you make sure the voltage is well within the max/min limits, once for receive and then for transmit. A VCO with its slug set to 'almost' cover all 40 can buzz on a channel that it 'almost' locks onto. When L19 is almost set right, a tiny touchup could be all that's needed. I never recommend touching it if you can't watch the tuning voltage and see how it responds to touching L19's slug. A slug that's cracked or has a loose sliver will show a jerky response. Should only see smooth change in tuning voltage as L19's slug is moved either way.

It really sounds as if L19 is set so that the tuning VCO tuning voltage bumps its head on the ceiling on the top channels.

73

That's good info. I had a guy bring me his Cobra 29 with a no receive issue. A slight adjustment on L19 brought the radio back to life. Just another thing to keep in mind, or add to the little black repair book.