[Boatanchors] HT-32

Sun May 26 13:21:52 EDT 2019

The HT-32 power transformer is the most common failure point in this family of transmitters, a trait it shares with the HT-30 and HT-37 (and perhaps others of that era).  I have HT-32, HT-32B, HT-37 and HT-30 transmitters and for all of these I converted the HV rectifier to SS with proper dropping resistor and inrush limiting so that the 5 volt filamentary winding for the HV rectifier is no longer in use with HV impressed upon it.

Although floating the transformer above ground will PROBABLY avoid this problem, I wouldn’t bet absolutely on the fault not manifesting itself in other ways if the transformer core/shell gets raised to HV level because you may then find the next weakness where you end up with a short to another winding from the core/shell which has now been raised to HV.  It seems much simpler and sure to me to address the root cause which is that troublesome 5 volt winding rather than floating the entire transformer assembly above ground.  For those who want to stay authentic, find a spot to mount a separate 5 volt transformer insulated for HV level and use that in place of the original HT-32 transformer winding.

And I have assisted enough “newbies” with vintage repair advice that I wouldn’t count on them understanding the significance of a red painted component as a warning that it is above ground.  At some point your gear will either go in a landfill or to a new owner; preferably the latter and you don’t want your prized rig to put the new owner into a landfill.  While I agree that people need to be smart and exercise personal responsibility, expecting new generations to understand the significances of informal safety alerts from decades ago isn’t realistic.  Sometimes it is necessary to take some steps that sacrifice some of the original safety but I don’t believe that this is a good case for such measures.

And there is a very high likelihood that as some of the current older owners grow even older that they will have a momentary lapse and forget not to rest and steady their arm on that convenient transformer arm rest while making a component voltage measurement.  I spent many years doing enterprise risk management and one of the basics is by the time one realizes the risk has been actualized it is too late to manage it.

Rodger WQ9E

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________________________________
From: boatanchors-bounces at mailman.qth.net <boatanchors-bounces at mailman.qth.net> on behalf of Rolynn Prechtl <k7dfw at clatskanie.com>
Sent: Sunday, May 26, 2019 12:09:43 PM
To: Boat Anchors List
Subject: Re: [Boatanchors] HT-32

It should be noted that insulating a transformer or choke from the chassis can be dangerous to anyone subsequently working on the unit because the device becomes a shock hazard if there is a short to the frame.

Duly noted.  However, for a variety of reasons, I don't think it is of
much concern.   If you give it some thought, you will likely agree.

==================================================================================

When insulating a xformer or choke from the chassis for preemptive reasons or because the choke is shorted to the frame, it was standard practice to paint the xformer or choke red as an indication of this action to future users. This was 60 years ago. We are such a kind and gentle society now so this may not fly with some.

I elevate the HV chokes on my KWS-1s with nylon standoffs as a preemptive measure.

After this discussion I may float some of the iron in my HT-32s also.

Rolynn
Clatskanie, OR
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