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Re: [Amps] power supply transformer

To: kg7hf@comcast.net, amps@contesting.com
Subject: Re: [Amps] power supply transformer
From: Peter Chadwick <g3rzp@g3rzp.wanadoo.co.uk>
Reply-to: g3rzp@g3rzp.wanadoo.co.uk
Date: Sun, 4 Feb 2007 12:16:45 +0100 (CET)
List-post: <mailto:amps@contesting.com>
Paul,
If you run the amp directly off the rectified 117 (or whatever) line voltage, 
tehre's an insulation requirement between the drains of teeh MOSFETS and the RF 
output winding, which is grounded. Similarly, between the 'ground' side of the 
amp (which could be at 120v above ground, depending which way round things are 
wired) and ground. So the specs manfred is talking about require that there's 
4kV insulation (and the creepage distance) between the real ground (that on 
your SO239 output socket) and the 'live' side of the RF output transformer. 
SImilarly on the input transformer. You also have a problem with bypass 
capacitors to the the input and output grounds, since any capacitor that goes 
to ground from one side of the line can lead to enough current flow through it 
to trip the GFCI.
All in all, I'd say it's more trouble than it's worth. The suggestion that a 
couple of 48volt high current SMPS in series could do the job sounds attractive.
I'm not convinced that, at the end of the day, at the 1000 - 1500 watt level, 
it isn't easier to use tubes, in spite of the high voltage problem....
73
Peter G3RZP
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