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From: "Frithiof Andreas Jensen"
Subject: Re: question on measuring temperarures at high voltages
Date: Thu, 24 Oct 2002 13:10:22 +0200
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"Kooner" wrote in message
> The LT1084 is used to power the filament or "heater" in a TWT.
When I made a 10 kV power supply for a magnetron, I used a small Flyback
based on an ETD39 core with the insulation provided by winding the
secondary/filament winding with 5 turns of 12 kV rated EHT cable. (I
selected the core from the need to fit the secondary into the window and
designed from there)!
The filament voltage was measured using a differential voltage divider and a
differential anplifier with some heavy filtering. We had some neat 100 MOhm
1% EHT resistors to use for the divider.
The switcher was an LM3905 "simple switcher" IC.
All this worked flawlessly, in spite of the magnetron bouncing from 0 to 10
kV - and the really neat thing was that the capacitance was very low and all
the electronics was sitting, accessible, at ground level. The filament leads
were taken out on top of the transformer and away from the PCB.
Hope this helps.
PS: Potting really sucks - it has to be the very last resort!
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