Fw: Re: [Collins] KWM2A repair question

Fri, 7 Jun 2002 18:45:06 -0500

Secondary emission from the plate is normal but due to the high voltage
on the 
plate, electrons are drawn back to it and, if during plate voltage swings
they are not,
the suppressor grid (which is at cathode potential) forces them back to
the plate.
Since there are wide spaces between wires on all these grids, most of the
electron
flow from the cathode to the plate is not affected.

As I understand screen grids, the main purpose is to decrease capacitance
between
the cathode and the plate, provide an electrostatic shield between the
two, and an
AC path back to the cathode. I am really not too clear on the whys, hows,
and effects
of screen secondary emission. Maybe Dr Jerry will weigh in and provide
some
clarification.

I was taught in the transition period from tubes to semiconductors with
the vast 
majority focused on semiconductors. I am trying, now, to get some of that
education
I missed on the old fire bottles.

73s  Kees K5BCQ

--------- Forwarded message ----------
From: "Rolynn Prechtl   K7DFW" <[email protected]>
To: "Collins2 LIST" <[email protected]>
Date: Fri, 7 Jun 2002 15:20:46 -0700
Subject: Re: [Collins] KWM2A repair question
Message-ID: <001101c20e71$933ae900$c3d7a3ce@pygora>
References: <[email protected]>

>Comments ?<

This man says........

"secondary emission often occurs under normal tube operation."

and it can be seen here.......

<http://www.frostburg.edu/dept/phys/latta/ee/2ndemission/secondary.htm>

That was the way I was taught.

Rolynn aka K7DFW

..._._

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