On Jul 28, 2006, at 6:23 AM, Larry Carman wrote:
> Another thought. Could impurities introduced during manufacturing
> of the
> different metals used in tube construction be associated with tube
> arcing?
Bits of pure metal can cause arcing. Example: Cu is famous for
growing whiskers in a vacuum. However, it is good to keep in mind
that fairly quiet arcing happens inside a vacuum, and that noisy
arcing happens in the atmosphere. IOW, if one hears a big-bang, it
was not from "barnacles" inside the tube.
>
> Larry N5BIP
>
>
>
> -----Original Message-----
>
> From: amps-bounces@contesting.com [mailto:amps-
> bounces@contesting.com] On
> Behalf Of Tom W8JI
>
> Sent: Friday, July 28, 2006 6:53 AM
>
> To: Amps Amps
>
> Subject: [Amps] Arc distance
>
>
>
> I wouldn't want people to walk away with the false idea that
> spacing is the
> only major parameter that determines arc distance in a given
> dielectric
> media. The shape is extremely important, as are any small sharp edges.
>
>
>
> A blunt smooth surface for a given spacing can have several times the
> voltage breakdown of a similar spacing with a sharp edge or even a
> very
> small sharp protrusion.
>
>
>
> People who think they can look at a complex structure and predict
> where it
> will break down based on spacing are kidding themselves and fooling
> anyone
> else who believes them.
>
>
>
> I suspect the incorrect bandswitch and capacitor breakdown voltages
> that are
> tossed out as "fact" come from looking at gaps or perhaps testing
> parts that
> are exceptionally smooth or testing under other best-case
> conditions, or
> maybe even just invented without any factual basis at all.
>
>
>
> 73, Tom W8JI
>
>
>
>
>
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>
R L MEASURES, AG6K. 805-386-3734
r@somis.org
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