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[AMPS] Re: Bent filaments

To: <amps@contesting.com>
Subject: [AMPS] Re: Bent filaments
From: G3SEK@ifwtech.demon.co.uk (Ian White, G3SEK)
Date: Mon, 14 Jul 1997 07:39:55 +0100
Phil Clements wrote:

>
>IMO the source of the current that bends the filaments is the same source
>that has sent Ip meters sailing out of their holes and across the room.
>It is the filter capacitor in the PS.

That certainly has to be true - aided by bad design that fails to limit
the maximum surge current, fails to protect the meters with diodes (BIG
diodes) and then forgets to turn off the mains supply to the
transformer.


>As amp manufacturers and home brewers began to push the envelope (no pun
>intended) with tubes running at maximum Ep and Ip there became less and less
>room (and time) for error. There now exists very cheap technology for removing
>the source of 99% of the "big bang" events by simply removing the PS filter
>cap. from the circuit in less than 3-5ms after a fault or arc occurs.
>
Details please! I've looked at a number of circuits, but they ain't
cheap because they require either a thyratron with unjustifiable space
and heater requirements, or a stack of thyristors rated at 3-4kV and
about 100A. If there are cheap sources of the latter, this Yorkshireman
of Scottish descent would like to know!


>No sources = no forces.
>
>(((73)))
>Phil, K5PC
>
>
>
>
>
>--
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73 from Ian G3SEK          Editor, 'The VHF/UHF DX Book'
                          'In Practice' columnist for RadCom (RSGB)
                           www.ifwtech.demon.co.uk/g3sek

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