Message-ID: <002301c5280e$22d70fe0$6507a8c0@Main>
From: "Alan Melia" <Alan.Melia@btinternet.com>
To: rsgb_lf_group@blacksheep.org
References: <311067511@web.de> <4234A260.10600@g3ysx.org.uk>
Date: Sun, 13 Mar 2005 20:49:19 -0000
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Subject: Re: LF: Re:Off topic, spark gaps, from dk8nd
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Hi Stwart, the same thing is used in surge arrestors for submarine cable
repeaters....the high voltage clamp is a gas tube, but being in the dark it
requires an little ionisation to be sure it strikes at the right voltage.
Some neons wont strike properly if you leave in the drawer for years.

By the way did you get my reply about the HiRose coax lead ?? or are all my
mails falling into your virus trap ??

Cheers de Alan G3NYK

----- Original Message -----
From: "Stewart Bryant" <stewart@g3ysx.org.uk>
To: <rsgb_lf_group@blacksheep.org>
Sent: 13 March 2005 20:28
Subject: Re: LF: Re:Off topic, spark gaps, from dk8nd


In interesting effect with spark gaps is the way that they change character
when they are not used. Apparently the metal surfaces grow whiskers which
are burned away with use. So if you do not use a spark gap for a while
the breakdown voltage lowers, and gradually increases as the whiskers get
burned off. I would therefore think that not only do you need to use a
radioactive source to ensure a source of ionization, but you would need
to run the gap in before getting an accurate result.

The ionization trick is also used in low jitter thyratrons, although some,
such as the infamous KN22B also provide a preionised gas supply
so as to ensure that the discharge characteristics are identical from
shot to shot.

- Stewart G3YSX