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[Amps] GPT-750 power supply

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Subject: [Amps] GPT-750 power supply
From: "Steve Flood" <>
Date: Thu, 9 Feb 2012 06:03:18 -0700
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I've been attempting to design a power supply using the big (100 lb) TF-193
transformer from a GPT-750 transmitter, the rating of which is 2800vdc @
750mA CCS, which is about what I'd like to get out of the supply for my
intended ICAS use with CW and SSB only.  (No AM or RTTY)


The transformer was designed for a choke-input and it has been a big problem
locating a suitable choke, particularly the actual 750mA 8-25H swinging
choke used in the GPT-750.


I have a few big chokes but none rated for 750mA.  The closest is a 12H
smoothing choke rated 600mA CCS which would probably be fine for current,
but the 12H is not enough inductance as it would only provide around 23%
regulation (in combo with a 12uF cap and 30k bleeder) as I calculated using
(Duncan PS design software).  It seems I need something more like 25 or 30H
to get down below 10% regulation.


So then, am I overlooking something in  this design,

Or should I just consider selling/trading this transformer for something
more modern for a capacitor-input supply?



Steve KK7UV


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