[Hallicrafters] HT-32B

[David C. Hallam]

Mike,

I have a HT-32B also and I offer the following.

If you replace the 5R4 with SS rectifiers don't worry about the increased
voltage.  The 6146's can take the extra voltage without any problem.  You do
need to adjust the low voltage (5V4 voltage) to keep it in line.

The primary cause of power transformer failure in the HT-32/HT-37 is a short
between the HV and 5 V rectifier windings.  Just replacing the vacuum tube
rectifiers with SS devices does nothing to help this.  There is still HV on
the rectifier windings.  What you need to do is disconnect the filament
leads from the rectifier tube sockets.

My biggest problem with electrolytics has been the speech amplifier bypass
capacitor.

Good luck, I've never been fortunate enough to have the original power
transformer last.  I have had several HT-32's (Mark 1, A, and B).

73

David C. Hallam
KC2JD

-----Original Message-----
From: hallicrafters-bounces at mailman.qth.net
[mailto:hallicrafters-bounces at mailman.qth.net]On Behalf Of Langston, Mike
Sent: Saturday, March 05, 2005 4:14 PM
To: Hallicrafters at mailman.qth.net
Subject: [Hallicrafters] HT-32B

I'm refurbishing a nice HT-32B. It has the original power transformer
and it checks good. I want to keep it that way. I have searched the
archives and I know this topic has been discussed before but I'm still
uncertain what causes the transformer failures.



1.      I am replacing both rectifier tubes with plug-in solid state
units and will use dropping resistors to obtain correct output voltages.
It seems like I remember some talk about disconnecting the 5V windings
from the tube sockets because they tend to short to the HV windings. Any
knowledge about this?
2.      I am replacing the bias supply selenium rectifier with an
appropriate value diode.
3.      I have replaced all electrolytic and paper capacitors.



Any comments, advice or other suggestions regarding modification of the
power supply would be appreciated.



 Thanks and 73,

Mike Langston KL7CD

Dallas-Ft. Worth

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