[Hallicrafters] SX-42 Mystery Capacitor & Sensitivity Modification

[Al Parker]

HI Peter,
    Just yesterday I decided to get back into my SX-42 to see why it's
overall sensitivity is down.  (haven't gotten very far yet.)
    C-127 is 100mf (electrolytic), and C-24 is .25 mf.  (note that the skem.
states, "condensers are in mfd unless otherwise specified.")
    It sounds like you're losing AVC on the FM band, it shouldn't be
overloading the front end.  Are you having similar problems on other bands?
It's been several months since I was into it last, and my memory is leakier
than any 3 BBOD's, so it'll take me some refreshing to get much farther on
your problem or mine.  It looks like there might be some AVC switching going
on at the 1st & 2nd RF secns.
    Keep us posted on your progress.
73,
Al, W8UT
New Bern, NC
BoatAnchors appreciated here
http://www.thecompendium.net/radio/
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----- Original Message -----
From: "PETER A. STRATIGOS" <peters7 at mindspring.com>
I recently re-capped my SX-42 which had previously had some of the caps
replaced.  I noticed that the center tap of teh sensitivity pot (R-12) had 2
capacitors in parallel going to the ground, C24 at .25mfd and C127 bearing a
schematic value of 100.  C127 is not identified in the parts list I question
the value of 100 (presumably pfd).

I also note that on the FM band, the sensitivity is very critical in that it
is easy to overload the front end of the receiver if the sensitivity control
is advanced much beyond 6 or 7.  Does anyone know whether there has been a
modification to this section of the receiver.  My SX-42 had a couple of
small electolytics going to ground off the center tap.

I would appreciate any thoughts anyone may have.

Peter N9HXW