[ARC5] OD3 VR Tube

[J. Forster]

In fact, the reason for using neons might not be because of diode
unavailability.

The inductive kick comes from the sudden opening of the circuit, and V=L
dI/dT applies. The neon lights allow a higher voltage to appear across the
coil, so the magnetic field collapses faster and the relay releases
faster. A diode or RC snubber would slow the coil release.

-John

==========




>
>
> I remember two incidents involving gas filled devices that stay in my
> memory.
>
> First is the ARC-27 Collins built aircraft UHF radio.  There was some NE2
> type neon lamps across several relays in the set as I recall that were
> suppressors for the "inductive pulse" that happens across the armature
> coil
> when it is de-energized.  (In those days using silicon diodes for this
> purpose was unknown!)  A couple of times I remember our "Shop expert" on
> the
> ARC-27 was stuck with sets that worked "OK" when the outer housing was
> removed but had glitches when the housing was replaced and pressurized!
> It
> turned out to be the "Photosensitivity" of certain of the neon lamps in
> the
> set.  As "Jimmy Hunt" said about the problem: "The damned lamps are scared
> of the dark!"
>
>
> The second case involved a "Mobile telephone decoder" which decoded the
> assigned telephone number of the VHF FM mobile telephone and rang a
> bell/buzzer when that set had an incoming telephone call.  Ma Bell used a
> mechanical device to do that job with the Motorola radios, but CMC
> (Canadian
> Marconi Company) designed an electronic device to do the same job that was
> more compact and had no moving parts.  The decoder used cold cathode
> triode
> subminiature tubes.  In order to do away with the "photoelectric" effect,
> again, NE-2 type neon bulbs were illuminating the tubes in order that they
> worked properly in darkness of an automobile trunk and the housing for the
> decoder.  These exhibited some very weird operation when the neon lamps
> failed at times!  Not always this happened, but enough times to drive you
> nuts until you got the dim or non working neon lamps replaced inside the
> decoder!
>
> That's my "gas filled devices" in the dark story.  Maybe the old "VR" tube
> regulators sometime do the same thing in the dark?  I never had any
> trouble,
> but then maybe I was always lucky?
>
> 73,
>
> Sandy W5TVW
> -----Original Message-----
> From: John Hutchins
> Sent: Friday, November 09, 2012 9:14 AM
> To: arc5 at mailman.qth.net
> 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
>
>
>
>
> On 11/8/2012 3:06 PM, Kenneth G. Gordon wrote:
>> For one thing, VR-tubes must be able to have some input from light to
>> "encourage" the formation of the internal "plasma"
>
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