[Hallicrafters] HT-32 to HT-37

[Glen Zook]

I don't usually recommend replacing the tube rectifiers with solid-state devices in most transmitters.  However, the Hallicrafters HT-32- series, the Hallicrafters HT-37, and the Collins 32V- series transmitters are definitely exceptions.  One needs to completely disconnect the 5.0 VAC windings so that the B+ is no longer on those.  You do get a slight reduction in transformer heating but the main thing is getting the high voltage from those windings.

I have run into the 5.0 VAC winding problems in the WRL Globe Champion 300 and 350 as well.
 
Glen, K9STH


Website:  http://k9sth.com


________________________________
 From: "K4PRF, B. L. Pratt" <pratt at knology.net>
To: hallicrafters at mailman.qth.net 
Sent: Monday, October 1, 2012 2:26 PM
Subject: [Hallicrafters] HT-32 to HT-37
 
Lesson learned the hard way.  If you have one of these fine transmitters 
and if it is still using the 5V4 low voltage rectifier, your power 
transformer is in danger.  If I remember correctly the problem is caused 
by a cathode to plate short in the 5V4 which opens the high voltage 
winding in the PT.  These transformers are very hard to find and 
expensive if you can find one.  I purchased a beautiful HT-32A several 
years back knowing that the PT was bad.  I was able to order a 
replacement PT from the Peter Dahl Co.  Expensive but a perfect 
replacement and runs very cool.  I replaced that 5V4 with a 5R4 in this 
and my HT-37.  I am told that those 5V4s have killed many a transformer 
and some call it a "death tube."  You might while you are in there 
replace the selenium bias rectifier with a silicon rectifier.  There 
have been many articles dealing with these modifications on the HT-32s 
and HT-37s.