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Re: [Amps] 3-500Z glitch resistor

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Subject: Re: [Amps] 3-500Z glitch resistor
From: David G4FTC <>
Date: Tue, 9 Sep 2008 05:09:26 +0000
List-post: <">>

>> True - but the arc will continue until the applied voltage has
>> dropped to quite
>> a low voltage, which without a crowbar, means that the resistor will
>> in effect
>> dissipate the energy in the capacitor bank, and providing the
>> resistor can
>> handle the peak current for the fraction of a second while the
>> capacitor
>> discharges then all will be well.
> FWIW, and right or wrong, I've used ordinary 1 or 2 Amp 3AG fuses
> in the HV lead to an amplifier to protect the tubes. Of course one would
> use an ordinary chassis mount fuse holder!! I placed the fuse inside
> the "sealed" power supply interlocked cabinet near the HV output
> connector. It worked when needed!

I tried that with a 2x 4CX250B 2 metre amp - when the fuse blows an arc forms
causing the glass to shatter. To compound matters the fuse wire evaporates and
deposits itself on the inside of the glass making the exercise less than 

High voltage fuses are available - but all that I've seen have been rated for 
operation. They are also quite long - a fuse for 6kV is about 120mm long, see

David G4FTC
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