[ARC5] Smart People - OT Why pentods fail (was Triodes & Pentodes)

[Dennis Monticelli]

Boy, I must have been asleep in physics class.  I don't remember any of
this electron breeding stuff!

Dennis AE6C


On Thu, Nov 14, 2013 at 12:05 PM, Bruce Long <coolbrucelong at yahoo.com>wrote:

> leslie is WRONG
>
> Electrons have no weight at all.   But they do come in pairs as male
> electrons and female electrons. Otherwise where would little electrons come
> from?  As they accumulate on the screen they have no place to go and they
> get crowded closer and closer together.   Eventually nature takes its
> course and they get hot?
>
> Understand?
>
>
>
>
>
> On Thursday, November 14, 2013 1:00 PM, Tim <timsamm at gmail.com> wrote:
>
> Hi Les - Thanks for explaining that....Very interesting!  I had previously
> thought that the main failure mode was caused by the vacuum leaking out.
> Who knew?
> Tim
> N6CC
>
>
> On Wed, Nov 13, 2013 at 10:16 PM, Leslie Smith <vk2bcu at operamail.com>
> wrote:
>
> >  "The screen failure will not be due to voltage over max but excess
> >  dissipation."
> > >
> > > I agree.
> > >
> > > Ken W7EKB
> >
> > Aw- Ken!
> > The above is nonsense, and I'm onto you.   :-;    It's not dissipation
> > (I-squared R heat) that causes the damage.
> >
> > The screen sags from the weight of accumulating electrons; the flow of
> > electrons is impeded by the thin wire.  :-(
> > We get the word, impedance from the latin, "impedire", meaning "to
> > shackle the feet" - and this is exactly what the thin grid wire does -
> > it impedes those little electronic feet.
> >
> > Note:  Screen-grids built from thicker wire allow the electrons to
> > escape; there is no sagging.  :-)
> > As for the the plate - it doesn't sag even a little.  Being thicker and
> > more robust, it can take the weight.
> >
> > As more electrons accumulate the screen grids sags, more and more, until
> > it touches the cathode.
> > The resulting short circuit  results in a decent "bang!".
> > This is the true failure mode.  Trust me.
> > I know nearly list-reader here will agree, particularly the better
> > informed readers.  :-) :-)  :-)
> >
> > Les
> >
> > (PS  I hope I don't get banned from  the list for stating the truth)
> >
> > --
> > http://www.fastmail.fm - A fast, anti-spam email service.
> >
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