Swan 700CX low voltage
 

Still having trouble with voltage drop when tuning my Swan 700CX.. At
the power supply the high voltage is well over the 800 V specified, but
when I switch to TUNE. The voltage rapidly drops to less than 400 V.
The output on cw is only about 50 watts and less than that on SSB. What
can I check with a voltmeter and where do I check? What parts might be
involved. I have tried 2 different power supplies with the same result

Don

Swan 700CX low voltage
 

Don wrote:
Still having trouble with voltage drop when tuning my Swan 700CX.. At
the power supply the high voltage is well over the 800 V specified, but
when I switch to TUNE. The voltage rapidly drops to less than 400 V.
The output on cw is only about 50 watts and less than that on SSB. What
can I check with a voltmeter and where do I check? What parts might be
involved. I have tried 2 different power supplies with the same result


Sounds like your final tubes are drawing excessive plate current.
Remove the finals (don't just remove the plate caps),
and repeat the voltage measurement.

73,
Ed Knobloch

Swan 700CX low voltage
 

I'm not sure w/o hunting the schematic, but if it has a voltage doubler,
ck the diodes. 1 could be bad.
73,
--
Al, W8UT
New Bern, NC
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