[AMRadio] 813 question

W1EOF w1eof at hamnutz.com
Tue Jan 31 19:45:56 EST 2006

I asked on the Tube Collector Assc list and got this response from Lane
who is a retired engineer from Eimac and one of the knowledgeable people
regarding the manufacturing of transmitting tubes:

"The leakage/breakage of metal to glass seals is primarily due to thermal or
mechanical stress. There should be no reason for tubes just lying around to
have any seal problems."
Lane Upton


Mark W1EOF

> -----Original Message-----
> From: charles free [mailto:mjcal77 at yahoo.com]
> Sent: Tuesday, January 31, 2006 10:13 AM
> To: amradio at mailman.qth.net
> Subject: [AMRadio] 813 question
> Hello all,
> I have a buddy who insists that if I don't get my old
> 813's out of the "future project" box and fire the
> filaments up on them now and then, the base seals will
> eventually deteriorate.  I guess he is talking about
> the adhesive that secures the base to the bulb.  I
> don't see how the glass envelope where the leads pass
> through the glass could be affected by lack of use,
> but maybe one of you folks has experience with this.
> Anybody heard of this one before?
> W4MEC, Charlie in NC

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