[Hammarlund] HQ-110C Help!!!

[Mike Lopez]

Found the problem ! It's dumb and embarrassing! Although the main filter in the power supply was replaced about five years ago, one of the 20 mF caps failed again. I overlooked it since it was new and the radio didn't humm or exhibit any typical characteristics of a bad filter. Apparently, there was enough capacity with one filter and the choke to operate the radio until it was taxed by the added BFO in the CW/ SSB mode. The squeal wasn't anything near 60 or 120 cycles so it never dawned on me that a bad filter was the culprit, until I looked at the B+ with the scope at the cap, and just happened to get across the bad one. B+ out in the set at the audio out tube looked fine until I set it into oscillation with the volume control, then the noise was of course everywhere! Live and learn......
Sigh,
Mike N8AZC
  ----- Original Message ----- 
  From: Mike Lopez 
  To: hammarlund at mailman.qth.net 
  Sent: Friday, December 19, 2008 4:49 PM
  Subject: [Hammarlund] HQ-110C Help!!!


  I have an HQ-110C with a weird problem that is driving me nuts!  When I switch to the SSB/CW mode, the radio goes in to continuous audio oscillation.....it screams. I have the AVC in the off position ( actually it doesn't make any difference, on, or off). I can stop the scream at -0- volume and bring it on at just below the 8 O'clock position ( I can barely open the volume control ). I can remove all of the tubes (except the 2 Audio tubes of course) and it still does it. I can the see the oscillation pretty much everywhere on the scope. It's not a humm, its like 1-2K cycles. The radio works in the AM mode and actually still works at minimum volume in SSB mode. I can hear a beat note at low volume when tuned to an AM signal so the BFO is working. I cleaned all the switches ...the problem doesn't seem to be there. Any clues????

  Thanks,
  Mike N8AZC


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