[Swan] What does a bad power supply filter sound like?

[KEN CUBILO]

Hi I have the same problem here with a cygnet 270 I  have traced the problem 
to the mixer circuit and I am in the process of rebuilding that circuit. I 
have replaced the tube with a couple of spares I had here to find the one 
most quiet but still need more work. I really don't think your problem is in 
the power supply

Ken W8WLC
----- Original Message ----- 
From: "John Williams" <ac6ts at n2.net>
To: <swan at mailman.qth.net>
Sent: Monday, January 24, 2005 8:43 AM
Subject: [Swan] What does a bad power supply filter sound like?


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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.


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