[ARC5] OD3 VR Tube

[Bill Fuqua]

Avalanche happens during arc  not glow discharge.
To produce two electrons requires second ionization potential to be reached.
This is a much higher energy  than the  first ionization potential.
Bill wa4lav


At 10:01 AM 11/9/2012 -0800, J. Forster wrote:
>VR tubes, and cold cathode rectifiers, do not perform well at low
>temperatures. They take longer to fire w/o some pre-ionization because the
>ion velocities are lower. The absolute temperature appears in the exponent
>of the avalanche equations, and at some reduced temperature (energy) the
>growing exponential becomes a decaying exponential.
>
>The math is very similar to a nuclear chain reaction, where a reactor is
>balanced on a knife edge between running away and shutting down. Controlo
>rods adjust the 'loop gain' of the reactor to exactly 1. Reactors do9 not
>work w/o active control.
>
>In fact, there is an EMER for the Canadian WS19 Mk III, which uses an 0Z4
>as a rectifier in the vibrator power supply, for arctic service. It
>describes the replacement of the cold cathode rectifier with a
>conventional tube w/ a filament.
>
>Best,
>
>-John
>
>=========
>
>
>
>
>
> >
> > ----- Original Message -----
> > From: "John Hutchins" <jphutch60bj at gmail.com>
> > To: <arc5 at mailman.qth.net>
> > Sent: Friday, November 09, 2012 7:14 AM
> > Subject: Re: [ARC5] OD3 VR Tube
> >
> >
> >> All -
> >>
> >> "--> For one thing, VR-tubes must be able to have some
> >> input from light to
> >> "encourage" the formation of the internal "plasma" "  <---
> >> What that's a new one?
> >>
> >> Lighter side:
> >> So the question is: Does a VR tube work in the dark,
> >> completely shielded from any form of radiation ?
> >> Similar to : does a tree falling in the forest make a
> >> sound....
> >>
> >> Hutch
> >>
> >      All too long ago I read an article explaining why some
> > VR tubes had some radio-active material in them.  I can't
> > remember exactly the conditions in which they were found not
> > to fire reliably but evidently it was fairly common. For
> > decades VR tubes were made without a built-in source of
> > ionization and seemed to work fine but some military
> > application came into being where they were not reliable.
> > Perhaps someone else's memory will be better about the
> > details.
> >
> >
> > --
> > Richard Knoppow
> > Los Angeles
> > WB6KBL
> > dickburk at ix.netcom.com
> >
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>
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