Fw: Re: [Collins] KWM2A repair question

Fri, 7 Jun 2002 14:23:07 -0500

(I saw a few comments on KWM-2 repair and decided to respond to the
attached note)

Yep, but they both (gas/grid emission) create unwanted electron flow and
effect the tube in the same way ....

One caused by knocking electrons off unwanted gas molecules inside the
tube envelope which causes 
the gas molecules to become positive ions. The ions take electrons from
the grid to become gas molecules again......This causes the grid to go
more positive and effects the grid bias level.

The second caused by some of the cathode coating material vaporizing,
over time, and depositing 
itself onto the grid resulting in grid electron emission........This
causes the grid to go more positive and 
effects the grid bias level.

Some testers are REAL picky in their adjustments and will trigger on 0.5
microamp as "fail" ...in real
circuits you probably won't see any effect until it's much higher than
that. The most sensitive area of
receivers which show this problem are AGC circuits (includes the S-meter
portion). 

73s  Kees K5BCQ 

--------- Forwarded message ----------
From: "Rolynn Prechtl   K7DFW" <[email protected]>
To: "Collins2 LIST" <[email protected]>
Date: Fri, 7 Jun 2002 10:40:59 -0700
Subject: Re: [Collins] KWM2A repair question
Message-ID: <00c701c20e4a$7d2460a0$b4d7a3ce@pygora>
References: <000801c20e2a$988a2200$6401a8c0@alex> 
        <002601c20e3b$3cbaf560$759d33cf@monk>

>  concerning
> "screen grid emission" of the 6146's in question....... doesn't the
presence
> of grid emission indicate the tube is "gassy"

Screen grid emission is secondary emission and has nothing to do with
gas.

K7DFW

..._._

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