[Hallicrafters] 32b

[Mark Shaum]

Subject: [Hallicrafters] 32b


> I have recently had the transformer in my ht32b re-wound and put back
in
> the chassis.
>
> Are there any initial settings that I need to make before putting it
on
> the air ? I have set the bias voltage according to the manual but
don't
> have the instruments to do much else at least with any confidence.
What
> are the groups thoughts ?
>

Most of the variances I have seen within the 32B series indicate that
the only
difference between power transformers is likely to be where the bias
winding
tap occurs on the secondary.  If you can set your bias to spec, your
transformer
likely matches your circuitry.

A few other notes, in case you have not checked much "downstream" of the
transformer yet:

The original bias rectifier CR102 is a selenium rectifier.  If you have
ever
smelled one of these when it shorts, you have probably already replaced
the thing with a silicon diode.  This might require increasing the value
of
R169 if the bias adjust pot doesn't have enough range to bring the bias
voltage down to spec.  Personal note,  I completely forgot about this in
my 32B,
and finally got around to replacing it this past weekend.

The LV rectifier filter caps, C93A and B - make sure they are reformed.
You don't want to replace that transformer again.  While at it, check
the LV
choke L127 for any shorts or excessive leakage to ground.

The HV side is a bit simpler.  C172 is an oil filled cap and likely
rather
robust.  No need to replace it unless it is leaking physically or overly
so
electrically.  The HV choke L124 should be checked as with the LV
choke for leakage to ground.  HV bleeder resistors (for what little
bleeding
they actually do, seeing how they total 440K!) should be checked for
tolerance.

Monitor all caps and chunks of iron present for any excessive heating
after the initial power-up.  This is where shorted turns in transformers
and chokes are going to become apparent that may not have been
notable during resistance checking.

73! - Mark  K9TR