John Williams wrote:
Group,

I need an expert opinion on a Swan power supply.
I have a 350c and 117xc. The transceiver has problems I will deal
with
later. For now, without any test gear, I want to rule out power
supply
because I'm putting it on ebay. The rig I'll have to sell seperately
to a
swan tech. on a reflector like this.

The radio has a consistant loud "CRACKLE" noise on receive. ( there
is No 60
cycle hum.) All bands, all volume levels, all rf gain levels,
with/without
antenna. crackle noise is steady. Without need to warm up.

This is my 4th swan and I always thought a bad filter cap would hum,
not
crackle. And I've had shorted caps blow fuses.

On transmit I get full power out without noise on seperate
monitor.(when it
decides to oscillate). Quiet carrier on CW an clean modulation on
ssb.

The rf detector works, because I can hear stations through the
crackle when
it decides to ocillate.

The rig also has an intermittant oscillator problem. RX and tx blink
on and
off as I turn vfo dial or turn rf gain knob or key relay over and
over.
There are no vfo "hot spots' where the oscillator quits or starts. It
is
random and changes spots in dial travel on each try. Same thing on
rf gain.
I'm not going to try to fix the rig, but is worth restoring to a
collecter
due to near museum cosmetics. All that later.

I just want to know if power supply is probably ok.

No other rigs to put supply on and no scope to look at wave forms.

I need an educated oppinion for now. Does a bad power supply CRACKLE?

Thanks for reading.
ac6ts Escondido, ca.

I believe your power supply is OK. sounds like an output transformer or
output tube to me. Unplug the output tube and see if it stops the
noise.If it doesn`t stop the noise ,it would be transformer
shorting..If the volume control changes the noise then it could be a
shorted IF can..NO 1 RULE, make sure all tubes are good first...good
luck W4PQW