AMRAD Spark Gaps

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Steve & Jackie Young by way of Terry Fritz <twftesla-at-uswest-dot-net>" <youngs-at-konnections-dot-com>

Ed,
What keeps the sparks from tracking across the fiber washer edge, thus
carbonizing it and ruining the gap?  Why does the gap stay in the center of
the disks?  Are the disks thicker in the middle and thus closer together in
the middle?
--Steve
----- Original Message -----
From: Tesla list <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Wednesday, December 20, 2000 9:56 PM
Subject: Re: Spark Gaps



> An AMRAD quenched gap is an antique, surplus from WWI, and used in
> spark transmitters!  Very rare now and prized by old junk collectors
> such as I am; the one I have is the only one I have ever seen in
> person.  AMRAD was the name of the outfit that made this particular one
> and ended up with a bunch on its hands when war contracts were
> cancelled. They then tried to sell them for amateur use, but the marked
> dried up as spark went out of style.  As for what it is, easier to send
> a picture than describe it, but its of conventional construction for
> that period.  Essentially it consists of many flat copper gaps in
> series, perhaps 1-1/2" in diameter and spaced about 1/32" apart.  They
> are separated by fiber washers and the whole assembly is held together
> by a clamping screw.  When it runs the oxygen inside is quickly used up,
> leaving mostly nitrogen.  The gap chambers are sealed from the
> atmosphere by the fiber washers, with the net result that the copper
> surfaces stay clean and pink after many hours of running.
>
> This type of quenched gap was used for the same reasons they are
> valuable for TC's.  They turn off fast......
>
> Ed