[Boatanchors] SX-101A hash noise- help

[Singley, Rodger]

David,

Sounds like something is oscillating for sure.  Can you hear the noise in another nearby receiver?  If so you can kill stages in the SX-101A while seeing what kills the noise in the test receiver.  I had one half of a push/pull output stage oscillating at 25 Khz in another receiver causing similar interference and a failure in any circuit could result in an oscillator.

Rodger WQ9E



-----Original Message-----
From: boatanchors-bounces at mailman.qth.net on behalf of David
Sent: Wed 11/25/2009 12:04 AM
To: boatanchors at mailman.qth.net
Subject: [Boatanchors] SX-101A hash noise- help
 
I'm restoring a dirty SX-101A.
It has very strong wideband noise approx every 5 KHz on every band.
I can't quite isolate it.  Logic tells me it's in the 1st LO.

Waveform from LO looks kinda non-sinusoidal- almost trigangular.  harmonics 
mixing it up?
Checked tube, grounds, components, but nothing obvious.

Anyone seen this before? 

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