Let me add a few comments:
Find the side of the filament with the lowest resistance reading to the
grid. That will give you the most direct path. Keep the tube upright
when applying power. A car battery has worked well for me.
Mike, W1NR
Radiodan W7RF wrote:
>
> Hi Skipp,
>
> My method is to provide a low voltage high current source (I have used 35+
> amp power supplies or even a car battery) and put one lead on the grid and
> one on the filament. It will burn through very quickly. Then take the tube
> with the lead still attached and tap it to get any loose flakes that are
> just about to short to come-on-down now.
>
> Guaranteed good for another hundred years!
>
> But seriously, my results have varied from getting good long term service to
> having the short reappear again very soon. Depends on how much damage you
> are willing to put up with vs. the cost of a new tube. With 3-500 tubes very
> inexpensive (relatively), the risk is high and the potential value low.
>
> 73, Dan Magro W7RF, (President WARC 1999, member SCDXC, SCCC)
> Manufacturers Rep & Distributor for HENRY RF Power Amplifiers.
> RF Applications Power Measuring equipment, See the VFD & WinWatt!
> www.radiodan.com <http://www.radiodan.com> RFpower@radiodan.com
> <mailto:RFpower@radiodan.com> A trip to our web site is worth the click!
>
> > -----Original Message-----
> > From: owner-amps@contesting.com [mailto:owner-amps@contesting.com]On
> > Behalf Of nospam4me@juno.com
> > Sent: Friday, December 31, 1999 10:57 AM
> > To: amps@contesting.com
> > Subject: [AMPS] knock a 3-500z short loose..?
> >
> >
> >
> >
> > I've got the source of much trouble here in my hand... a 3-500z with a
> > cathode to grid short. Anyone care to suggest a method to possibly open
> > the short. I won't trust the tube in an amplifier again, except maybe a
> > construction place holder.
> >
> > skipp
> >
> > ________________________________________________________________
> > YOU'RE PAYING TOO MUCH FOR THE INTERNET!
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> > Try it today - there's no risk! For your FREE software, visit:
> > http://dl.www.juno.com/get/tagj.
> >
> > --
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> >
> >
>
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--
**************** Give Every Man His Dew **************
Michael A. McCarthy, President
Everest Engineering Corporation, Consultants
4 Barnes Circle, Marlborough, MA 01752
(508) 460-6737, FAX (508) 460-7951
mailto:w1nr@eecorp.com
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