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Re: H.F.Tester (fwd)



---------- Forwarded message ----------
Date: Sat, 22 Feb 1997 22:04:50 GMT
From: Robert Michaels <robert.michaels-at-online.sme-dot-org>
To: mod1-at-pupman-dot-com
Subject: Re:  H.F.Tester (fwd)


M> Plug it in and if it kicks out sparks of 3/4" plus it
M>is probably the standard vacuum tester (and destroyer of weak
M>seals) commonly used in vacuum work.  May have a vibrator adjustment
M>or something of the kind.  Ones I have seen are almost always
M>packaged in brown bakelite, with fairly heavy "needle" on the
M>HV end.
M> No clue where you might get information, unless you can
M>look in (old, I assume) scientific instrument catalogs (Cenco,
M>here in the US, for instance) or vacuum supply catalog.
M>Ed Phillips

        These device are alive and well and being imported into
        the USA by several firms which advertise in "Thomas
        Register of Manufacturers".  Several such advertisements
        offer literature, catalogs, etc.   (Any who have trouble
        locating "Thomas Register ..."  [at your library or em-
        ployer's purchasing dept], e-mail me and I'll see what
        I can do).

                Aside to our Euro/Asian friends: "Thomas ..."
                is an encyclopedic (15 or 20 volume) purchasing
                directory listing almost every firm producing
                industrial/commercial hard goods in the US.

        The purpose of these devices is to test for leaks in a
        high-vacuum system.  The spark from the tester is drawn
        to small cracks and leaks in =glass= apparatus
        and in a sense "points them out"   (Why, I do not know).
        It can find leaks and cracks far too small to see (and
        which therefore have very slow leakage rates).  This is
        indispensable in serious high-vacuum work which work is
        commonplace in physics, electronics, and chemistry.

        The pointed structure on the end is not a needle per se
        but a spark gap.  Those having one of these coils will
        be edified by applying the probes of an ohmmeter to
        the top and bottom of the pointed structure.

        These are Oudin coils (=not= Tesla coils).  The last time
        I posted my frank opinion of Mr. Oudin and his coils the
        flames did not die down for three weeks straight.  Forgive
        me if I refrain from repeating my refrain (which is a tau-
        tology, since a refrain =is= a repetition).  All my asbestos
        suits are at the cleaners.

        BTW -- The adjustment knob at the bottom of the coil (for
        peaking the vibrator) should =never= be used to shut the
        coil off.   Some older coils will tolerate this treatment
        for a while.  The newer ones are apt to burn out in a
        trice.  They are hard to disassemble and hard to rewind
        (and they're Oudin coils).  You have been warned.

                                  In a vacuum,

                                  Robert Michaels
                                  robert.michaels-at-online.sme-dot-org

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