Re: thyratron

Subject:  Re: thyratron
  Date:  Tue, 17 Jun 1997 01:27:30 -0400 (EDT)
  From:  richard hull <rhull-at-richmond.infi-dot-net>
    To:  Tesla List <tesla-at-pupman-dot-com>

At 01:19 AM 6/13/97 -0500, you wrote:
>Subject:    Re: RE- Secondary wire & insu
>  Date:    Thu, 12 Jun 1997 17:40:46 -0700 (PDT)
>  From:   "Edward V. Phillips" <ed-at-alumni.caltech.edu>
>    To:    tesla-at-pupman-dot-com
>"I just mailed it out last night.
>RG-214 dual braid coax 6 turns (can be five)  about 25uh.  3" tall 12.5"
>diameter.  Capacitor is .0068
>Richard Hull, TCBOR"
>        I saw that one.  What I really want to know (and should
>have been more explicit about) is the circuit for the thyratron
>switch, and in particular if you've rigged things so that the
>current through it doesn't want to "go negative".  If you
>described that I REALLY missed it!

The key is to release the grid drive way before the negative excursion
the first current peak's first zero crossing.  Thus for a 500KHZ system
means a 1 micro second grid pulse.  The tube turns off so completely
there is just no real reverse current in the tube.  Although I am sure a
nanoseconds worth might exist as the coil's primary reverses polarity,
this slams the tube off.  I have seen no detrimental results from the
circuit.  I keep a close eye on the tube for sparkles of cathode
being ripped away.  So far I have seen none and observed no reverse
on the wideband pearson C.T.

In the old days they used a vacuum diode to limit reversal problems and
placed it across the thyratron in reverse.  I have no such circuit or

Richard Hull, TCBOR