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Re: [Amps] "Tubes 201" - How Vacuum Tubes Really Work

To: <craxd1@verizon.net>, <amps@contesting.com>
Subject: Re: [Amps] "Tubes 201" - How Vacuum Tubes Really Work
From: "Tom W8JI" <w8ji@w8ji.com>
Date: Mon, 24 Jul 2006 19:48:59 -0400
List-post: <mailto:amps@contesting.com>
Will wrote:

<It's impossible to run one temperature on zirconium.

 I guess Eimac is lucky they quit making 3-500Z's, since the 
gray power on the anode is the getter and it is zirconium.


>By the way, Terman on page 187 of my Third edition warns
>about excessive resistance in grid leads. Terman states, "
>If the resistance in the grid circuit is high enough, this
>process can become cumulative, resulting in the control 
>grid
>potential suddenly becoming positive and causing the
>**destruction** of the tube as a result of excessive plate
>current."

Will wrote:
<<Nowhere in the whole paragraph about gassy tubes (Effect 
of Gas upon Tube Characteristics) which is under part 13, 
page 316 in this book, says a grid became positive! It only 
says this can cause a grid to become "less negative"!>>

The text of the page in the third editon  of Terman is at 
the bottom of: 
http://www.w8ji.com/fusing_and_floating_grids.htm

Anyone who wants can look and see what it says for 
themselves.

73 Tom 


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