[Heathkit] DX-40 Transformers?

[Gary]

I have rewound several of the DX-20, DX-40 and HX-11 power transformers. 9 
times out of 10 there is a short between the filament and the hv winding. 
The original insulation used was not up to snuff as far as I am concerned. 
When I rewind these, I use 15 mil nomex layered between the different 
windings and have not had one go bad yet. Regards,
Gary...WZ1M
---------------------------------------------------------------------------------------------------------------------
----- Original Message ----- 
From: "Glen Zook" <gzook at yahoo.com>
To: <Heathkit at mailman.qth.net>; <rhulett1 at comcast.net>
Sent: Saturday, August 21, 2010 11:09 AM
Subject: Re: [Heathkit] DX-40 Transformers?


Remove the 5U4 rectifier tube and replace it with solid-state.  Disconnect 
both ends of the 5.0 VAC rectifier tube filament winding to get the 
rectified B+ off of the transformer.  This helps.

Glen, K9STH

Website:  http://k9sth.com


--- On Sat, 8/21/10, rhulett1 at comcast.net <rhulett1 at comcast.net> wrote:

Next question is whether there are operational procedures ( like keeping 
plate current below 100ma for example ) that will prevent transformer 
destruction. Seems like I've read that the trouble is with the filament 
winding? Maybe nothing to prevent failure?



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