----- Original Message -----
From: "measures" <2@vc.net>
To: "AMPS" <amps@contesting.com>
Sent: Monday, April 16, 2001 2:41 AM
Subject: Re: [AMPS] Zener screen supplies
>
> >
> >measures wrote:
> >>
> >>>
> >>>Tom Rauch wrote:
> >>>>
> >>>>You need enough capacitance near the screen to absorb the initial
spike
> >>>>Neither a MOV or gas tube will work well by itself. Even a modest
> >>>>overvoltage is too much for regulators. Slow the transient down.
> >>>>
> >>>>Actually, the MOV is a last resort just to protect the socket
> >>>>capacitor...as would be a gas tube.
> >>>
> >>>The MOV or gas tube at the screen terminal is actually the *first* line
> >>>of defense because that is where the arc hits. Tom correctly identifies
> >>>that the screen bypass capacitor in the socket is at least as valuable
> >>>and important as the tube. The tube may survive,
> >>
> >>A tube that arced is already a proven leaker.
> >>
> >
> >Not true, on two counts.
> >
> >1. Sometimes the arc is due to an RF problem external to the tube, such
> >as a high SWR.
> >
> >2. Sometimes the arc isn't any kind of RF problem at all. Many of mine
> >have been due to insects (or loose parts shredded by the blower) being
> >carried in the airstream until they lodge in the chimney between the
> >anode and the screen ring.
> >
> ? How did the insects get inside the tubes?
>
It amazes me how different the English language is over here :)
until they (the insects or loose parts) are carried in the airstream until
they (the insects or loose parts) are lodged in the chimney between the
anode(external bit of the tube) and the screen ring (of the socket). I hope
the translation has helped Rich :)
Not taurine feculance!
Regards
Conrad G0RUZ
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