Message-ID: <4234A260.10600@g3ysx.org.uk>
Date: Sun, 13 Mar 2005 20:28:16 +0000
From: Stewart Bryant <stewart@g3ysx.org.uk>
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Subject: Re: LF: Re:Off topic, spark gaps, from dk8nd
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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

Hans-Albrecht Haffa wrote:

>Dear Dick, 
>spark gaps are a genuine way of measuring high voltages in a HV-Laboratory. There exist tables for DC and AC 50 Hz. Spark gaps must be used, as it is impossible to use a rotary swich in a meter at 100kV or more. oen of the spheres is doped with an radioactive element to cause discharge always at the same place on the spheres surface.  Break down voltage is checked with observers eye and ears and depends on Voltage (ac/dc, HF), temperature, humidity and absolute air pressure. An uncertainity of about +-2% may be obtained in voltage-measurements. A gross value for break down voltage is 30 kV/cm. Try to get into contact with an advanced engineering school teaching energy technics, machine engineering and High frequency technics. If the schools is specialized on contemporary data processing, electronics and international economy, You are wrong, so an traditional institution is recommended. In my case it is "Georg-Simon-Ohm-Fachhochschule Nürnberg".
>
>73,
>Hans-Albrecht
>DK 8 ND
>
>
>-----Ursprüngliche Nachricht (HTML) wurde als Anlage beigefügt.-----
>Von:      rsgb_lf_group@blacksheep.org
>Gesendet: 10.03.05 20:51:22
>An:       "Hans-Albrecht Haffa" <dk8nd@web.de>
>Betreff:  Re: LF: Off topic
>
>
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