[Hallicrafters] HT-32B

[Jack Schrader]

First thing you need to do is solid state both of the rectifier tubes!!! 
Hopefully you have not shorted the xfmr already. Do not apply any voltage to 
that transformer with the tube rectifiers in place or you will shortly have 
a blown transformer.

Give me you telephone no. and I will call you with more info.

73    Jack   w1jhs

-----Original Message----- 
From: Langston, Mike
Sent: Sunday, June 22, 2014 8:44 PM
To: Hallicrafters at mailman.qth.net ; tetrode at googlegroups.com
Subject: [Hallicrafters] HT-32B

After many suggestions on how to check my concern about the power xfrmr, I 
have done the following:


*         Replaced both final tubes with a new matched set

*         Replaced both HV ceramic caps (top and bottom of rf choke)

I put the primary on a variac and inserted a Simpson milliameter in the 
plate circuit with a VTVM measuring plate voltage. The output was run 
through a wattmeter to a dummy load. Here's what happens:

I ran the variac up to a plate voltage of 500. After about one minute, the 
voltage dropped back to 375 and the plate circuit began to draw current. I 
ran the voltage back up to 500 and noted plate current as follows:


*         500 v = 24 ma

*         600 v = 34 ma

*         700 v = 46 ma

*         800 v = 70 ma

All of the above is with no drive. Switching to MOX and gradually applying 
rf while peaking drive and final tune, I get about 10 watts out at 800 volts 
with plate current measuring about 200 ma. The plate current at this point 
starts to rise slowly but accelerates rapidly. How far it might go is 
unknown because I chicken out and cut the rf drive back before smoking 
something.

Disconnecting the HV lead at the input to the rf choke and measuring HV at 
that point (output of filter choke/capacitor - no load) with the variac at 
max, I get 1090 v. This remains steady so the transformer, choke and filter 
cap seem to be fine.

I know this has got to be something simple to find if I just knew how to go 
about doing it.

Any further suggestions on what to try next would be appreciated.

Mike KL7CD
______________________________________________________________
Hallicrafters mailing list
Home: http://mailman.qth.net/mailman/listinfo/hallicrafters
Help: http://mailman.qth.net/mmfaq.htm
Post: mailto:Hallicrafters at mailman.qth.net

List Administrator: Duane Fischer, W8DBF
** For Assistance: dfischer at usol.com **


This list hosted by: http://www.qsl.net
Please help support this email list: http://www.qsl.net/donate.html