SPECTRA Tx Problem...New Information-Power Control?

[PGrund]

I have had it on the bench since my posting and I have made several mistakes on the symptoms..

The unit has a few milli-watts of power and on channel at the input to the PA deck section at the coax connector...

The radio will put out full power if I source 12 vdc via a 27k resistor at he collector of the first low level amp.

There is some problem in the low level section of the power control circuit... I see a small 8pin IC and other components.

Has anyone had any similar problems in the power control area.

Thanks to all who have been helping.

Phil
[email protected]

[larryepage]

I had a UHF Spectra with a problem almost exactly as you describe. Turned out the only problem was a bad solder connection on one of the coupling coils on the PA board. I don't have the schematic in front of me, but as I recall, the PA transistors are all biased to the power rail via these coils.

Heating and cooling of the board during transmit cycles can eventually cause solder connections to fail.

Regards,
LP