[Hallicrafters] Hummmmmm.......

[Edward B Richards]

Sounds like a heater-cathode leakage in one of the tubes. Probably I.F.
or BFO tube.

73, Ed Richards K6UUZ
Simi Valley, Ca 93065
Home of the Air Force 1 pavilion

On Sun, 14 Jan 2007 19:59:14 -0800 (PST) Joe Bob Brunson
<yowje at yahoo.com> writes:
>   I have a problem which is driving me up the wall...
> 
> I have several Hallicrafters receivers (S-20R, SX-24,
> S-22R, SX-28 and S-40), and all of them have the same
> problem.  At lower frequencies (40 meters and below on
> some, 20 meters and below on others) when listening to
> SSB or CW, everything sounds really peachy.  15 meters
> and above (20 meters on the S-22R), there is a hum
> which is only apparent using the BFO.  AM reception on
> these frequencies sounds fine. The S-22R, SX-24 and
> S-40 have been re-capped, the SX-28 is almost
> original, and the S-20R hasn't been re-capped, but has
> had this problem as long as I have owned it (since
> 1970).
> 
> I have tried several mixer tubes in each one, checked
> lead dress, voltages, resistances, etc. to no avail. 
> I've even been tempted to run DC to the tube heaters,
> but would rather not...I assume the receivers sounded
> fine on these bands when new, so I don't want to
> re-engineer things if I don't have to.
> 
> Any ideas?
> 
> 73,
> 
> WB6FQL
> 
> 
>  
>
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