From fto–(at)–etcom.com Mon Jun 26 21:11:15 CDT 1995
Article: 1974 of alt.guitar.amps
Newsgroups: alt.guitar.amps
Path: geraldo.cc.utexas.edu!cs.utexas.edu!news.sprintlink.net!noc.netcom.net!netcom.com!netcom10.netcom.com!ftom
From: fto–(at)–etcom.com (Tom May)
Subject: Re: Phase splitters: new vs old
In-Reply-To: mgarvi–(at)–anix.com’s message of 25 Jun 1995 03:08:25 -0400
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References: <3rgpq6$i5--(at)--anix2.panix.com> <3rl7ai$cr--(at)--ver.mhv.net>
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Date: Mon, 26 Jun 1995 22:40:25 GMT
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In article <3sj219$8i--(at)--anix2.panix.com> mgarvi–(at)–anix.com (Mark Garvin) writes:

>There *is* something else, too. I’ve been hesitant to mention this
>cause it’s pretty obscure, but I’ve slowly been coming to accept it.
>(Again, I haven’t reproduced this–it’s a long-term effect):
>I understand that the higher DC path can let ionization/residual
>charge buildup within the tube, which ionizes yet more of the
>residual gases. The increased ionized gas compounds the effect
>and it avalanches. The tube ‘goes gassy’ much earlier.

>How’s that for urban tube folklore? Probably true, tho.

I thought that was the effect you were talking about all along. I
quote from the RCA Receiving Tube Manual where this effect is
described: “Also, the grid resistor of the following stage should not
be too large, the actual maximum value being dependent on the
particular tube type. This precaution is necessary because all tubes
contain minute amounts of residual gas which cause a minute flow of
current through the grid resistor. If the grid resistor is too large,
the positive bias developed by the flow of this current through the
resistor decreases the normal negative bias and produces an increase
in plate current. This increased current may overheat the tube and
cause liberation of more gas which, in turn, will cause further
decrease in bias. The action is cumulative and results in a runaway
condition which can destroy the tube.”

Is there another effect which can be cured by cycling the power?
—
Tom.