[Hallicrafters] SX-24 Questions

[Mike Everette]

Darryl,

Do you have a manual?

You can get one at http://bama.sbc.edu or
www.nostalgiaair.org

If you don't have one, get one before going any
further.

Have you done any recapping yet?

The old electrolytics need to be replaced, for sure. 
Beyond that, odds are, you will find numerous leaky or
perhaps even shorted wax capacitors.  Don't bother
testing them -- shotgun 'em.  You may find that there
are a couple or three "buried" under the coils and
band switch, especially around the oscillator/mixer
tube.  Be VERY careful working in this area.  Don't
try to disassemble the front end; it is dangerous. 
Very easy to break something irreplaceable; besides,
some of the sheet metal screws that hold things
together in this area are brittle and will break at
the slightest overtightening when you put them back. 
Removing the broken screws is no fun.  Been there,
done that.

If you don't have patience, get it.  

You may even need some special long-reach nippers and
a very thin soldering iron with a 45-degree bent tip,
to work in this area.  Yes, it CAN be done.  A vacuum
solder sucker with a long-reach tip, and some solder
wick, are extremely helpful too.

You will have to take the chassis out of the cabinet
to be able to get to some of these caps.  Be sure to
remove the dials from the shafts and put them in a
safe place.  They are brittle, easily broken and not
easily replaced.  To get the receiver out of the case,
you need to remove all knobs, control nuts, and the
screws in the bottom that contact the chassis.

By the way, DO NOT use any kind of liquid cleaner on
the inked side of the dials.  It will destroy the
markings.  Same goes for the dial windows.

Be prepared to find many out-of-tolerance resistors as
well.  I recently finished up an SX-25 which is very
similar to the 24.  My receiver needed more than 3/4
of the carbon resistors replaced.  The most typical
case involved 100k ohm units that actually measured
almost twice the marked value; but all resistors are
suspect.

You may have a cumulative effect of bad parts that
adds up to a deaf receiver.

One thing that may be happening, is that a cathode or
grid-leak resistor in the HF Oscillator circuit has
gone way over value and the oscillator injection is
down, or the oscillator is not working at higher
frequencies.

Of course, some whiz-bang may have gone wild with a
screwdriver, trying to "tighten up" all those "loose"
screws on the padders and trimmers, and really messed
up the alignment!  In that case I'd start by injecting
455 KHz into the IF and peaking that up, then see what
difference it makes, before going into the front end.

Hope this helps.

73

Mike
WA4DLF



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