Re: Relativity question

From: bz (bz+sp_at_ch100-5.chem.lsu.edu)
Date: 03/24/05 

Date: Thu, 24 Mar 2005 01:45:03 +0000 (UTC)

RP <no_mail_no_spam@yahoo.com> wrote in news:3aeihpF6a5rd6U1
@individual.net:

> in many vacuum tubes the electron beam
> is accompanied by a reverse flow of positive ions,

When vacuum tubes get gassy, it is time to replace them.

You can tell when a vacuum tube is gassy. The positive ions GLOW because
they collide with the electrons, are excited and emit photons.

Also the current increases dramatically. Grids become less effective at
controlling the plate current, signal output decreases, efficiency
decreases, Waste heat increases. Screen grid current flow goes up and can
damage the screen grid. The plate heats. Under extreme conditions, holes
can melt in the plate or the tube's glass envelope can soften and sag or
even puncture.

Ions impacting on the cathode cause it to overheat and damage the
thermionic coating on the cathode.

In short, gassy tubes (unless they are voltage regulators, thyratrons or
mercury vapor rectifiers) are bad tubes. Gassy vacuum tubes are bad vacuum
tubes. 

-- 
bz
please pardon my infinite ignorance, the set-of-things-I-do-not-know is an 
infinite set.
bz+sp@ch100-5.chem.lsu.edu   remove ch100-5 to avoid spam trap
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