>
>
>----- 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
>
? We have been discussing arcs inside the tube.
- Rich..., 805.386.3734, www.vcnet.com/measures.
end
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