[Hallicrafters] SX-28A Oscillator Interference

[Glen Zook]

Before really "digging" into the "innards", try
slightly loosening and then retightening EVERY screw,
machine screw, nut, bolt, that there is on the chassis
(of course not the alignment capacitors - old joke but
true - people used to bring in their radios to the
repair shop that I worked at in high school and said
that they "tightened the screws" and the radio quit
playing!).  Actually, virtually every ground that is
made in the receiver is made through one of these. 
Over the years they either come slightly loose, or
build up corrosion.  By loosening slightly and then
retightening them, you again make good ground
connections.

Remember, every terminal strip that is on the chassis
usually has a ground connection.  Also, many "boat
anchors" make grounds through the rings that are
around some of the tube sockets.

Also, make sure that the "can" on any chassis mounted
electrolytics that are supposed to go to ground are
actually getting to ground.  Many of these were just
"twisted" in place and that works loose over the
years.

I have "fixed" many "strange" problems as well as
intermittents in all sorts of equipment by doing the
"screw" bit.  The Heath SB-Line and HW-Line of
equipment are very bad about this as well.

Glen, K9STH


--- jim <jimw at premier1.net> wrote:
> I have a SX-28A that receives on all bands, but
> produces a high pitched 
> tone or oscillation every few mhz as it is tuned.

Has anyone got ideas what might be causing the
oscillation noise?  Maybe parts placement or coupling?


=====
Glen, K9STH

Web sites

http://home.comcast.net/~k9sth
http://home.comcast.net/~zcomco

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