RE: vacuum tube construction. (fwd)

["Tesla list" <tesla@xxxxxxxxxx>]

---------- Forwarded message ----------
Date: Mon, 13 Aug 2007 17:00:29 -0400
From: Nick Andrews <nicothefabulous@xxxxxxxxxxx>
To: Tesla list <tesla@xxxxxxxxxx>
Subject: RE: vacuum tube construction. (fwd)

Jeff,Look for ebay seller geoelectronics.  Geo sells and calibrates Geiger counters and such in MO.  Also check out the CDV700Club Yahell group.Nick A > Date: Mon, 13 Aug 2007 13:28:27 -0600> From: tesla@xxxxxxxxxx> To: tesla@xxxxxxxxxx> Subject: RE: vacuum tube construction. (fwd)> > > ---------- Forwarded message ----------> Date: Mon, 13 Aug 2007 12:13:06 -0700> From: Frank <fxrays@xxxxxxxxxx>> To: Tesla list <tesla@xxxxxxxxxx>> Subject: RE: vacuum tube construction. (fwd)> > All this tube is is a simple Geissler tube.> The vacuum levels are not high enough to ever generate X rays.> You need a hard vacuum and a diffusion or turbine pump along with a > scavenging method to pump the tube down hard enough to be able to > generate X rays.  Tubes that can be taken apart for cleaning will not > have seals good enough to hold an X ray vacuum.> Since the tube conducts, it will not work as a spark gap at all, > basically it is a neon tube type effect and it will just glow as the > voltage is applied and then turn into a voltage regulator and get > brighter with more current until the electrodes start to get hot and > they will out gas and lower the vacuum until the tube stops conducting.> > Large mercury arc rectifiers will work as a switch with some > additional circuitry but are not available anymore. Those were used > on some of the early wireless transmitters.> > Dosimeters are a device to measure radiation over time, basically a > charged capacitor that is discharged by radiation. Usually they are > calibrated in REMS and if they ever register, the amount of radiation > is enormous and you better run!> > A CD Geiger counter, Model CDV 700-XX is a good counter to measure > radiation in small amounts and can be used to detect X rays. These > are on Ebay all the time.> > Frank> > >Quoting Tesla list <tesla@xxxxxxxxxx>:> >> > >> > > ---------- Forwarded message ----------> > > Date: Mon, 13 Aug 2007 07:52:30 -0400> > > From: Jeff Fink <revtec@xxxxxxx>> > > To: 'Tesla list' <tesla@xxxxxxxxxx>> > > Subject: RE: vacuum tube construction. (fwd)> > >> > > I am new to this list and ironically this is the first post I have read.> > >> > > Over the years I have been experimenting with massive cold cathode vacuum> > > tube diodes, looking at the phenomena of PAGD (pulsed abnormal glow> > > discharge).  I was wondering if the tube could be used as the > > spark gap on a> > > TC.  I understand there could be X-ray production, but would it be> > > dangerous?  Another question: Would the X-rays register on 60's vintage> > > Civil Defense radiation dosimeters?> > >> > > My tube design is incredibly easy to build when you consider that there is> > > no grid or filament, though some machine shop work is > > required.  They can be> > > easily disassembled for cleaning and modification.> > >> > > My largest is 12" diameter, using a 12" by 3" long by 1/2" wall > > pyrex tube.> > >> > > The anode and cathode are 3/4" aluminum plates.  The tube sets into a> > > circular groove on each plate and is sealed with a 3/16" O'rings > > coated with> > > vacuum grease.  A hole and fitting on the cathode plate provides connection> > > to a refrigeration vacuum pump sold by Grainger, which developes > > a very nice> > > vacuum.  The tube lights off on only 600 volts.> > >> > > Jeff> >> >It wouldn't work so well for a TC because TCs have discharge currents in the> >hundreds to thousands of amps and I don't think a discharge tube would handle> >that too well for long. Also the 600V firing is kind of low so you> >wouldn't get> >much energy output from the coil.> >