[Hallicrafters] S-38 BFO and hum problem

[Rich Oliver]

Craig,

I have seen behavior like you describe with a rubbing voice coil in the 
speaker.  The catch (pun intended) is that you also get lots of 
crackling in the sound when this happens and you did not mention any 
crackling.  To check for a rubbing voice coil push lightly on the outer 
part of the speaker cone with your thumb.  If there is rubbing going on 
a bit of pushing will change it.  If you pick a spot that relieves the 
rubbing the volume will increase and the crackling will stop.  If you 
pick a spot that causes the coil to rub harder the audio will usually 
die altogether.

73 and QMC, Rich

Craig Roberts wrote:
> Here's another oddity that may provide someone with a clue to finding my
> S-38's low BFO injection problem: when I switch the BFO circuit in (CW
> position of AM/CW switch) the receiver's audio and possibly sensitivity
> increases dramatically as a slightly audible beat note is added. I've never
> had a receiver with this problem, so it's quite baffling.
> 
> Any ideas?
> 
> Thanks again,
> 
> Craig
> W3CRR
> 
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