[ARC5] OD3 VR Tube

[J. Forster]

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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