[Hallicrafters] Hummmmmm.......

[Joe Bob Brunson]

  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


 
____________________________________________________________________________________
Finding fabulous fares is fun.  
Let Yahoo! FareChase search your favorite travel sites to find flight and hotel bargains.
http://farechase.yahoo.com/promo-generic-14795097