"Reverse" modulation hum

[Bob Jackson]

Aha!  Bad AGC cap! AGC goes nuts w/o a signal. Thanks to Jim Simmons - should've occurred to me - my bad. Thanks to all that replied.

Bob  AG5X

PS - This is a "Globe'ciever" - modest 4-tube gen. cvg. rig  from days of yore.
  ----- Original Message ----- 
  From: J. Forster 
  To: Bob Jackson 
  Cc: boatanchors at lists.tempe.gov 
  Sent: Monday, November 29, 2010 5:25 PM
  Subject: Re: [BOATANCHORS-TEMPE] "Reverse" modulation hum


  Heater-cathode leakage or bad bypass cap in the IF?

  The AGC cranks up the gain w/o a signal.

  FWIW,

  -John

  ===============


  > Strong humming noise heard only between stations, not while tuned to a
  > station. Doesn't sound the same as pwr supply "bad caps" hum and is
  > stronger. Ideas ???
  >
  >
  > Bob  AG5X
  >
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