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

[Keith Dutson]

I am not talking about AFTER the fuse blows.  What current CAUSED it to
blow?

Thanks.

Keith

-----Original Message-----
From: amps-bounces at contesting.com [mailto:amps-bounces at contesting.com] On
Behalf Of Will Matney
Sent: Monday, July 24, 2006 9:33 PM
To: amps at contesting.com
Subject: Re: [Amps] "Tubes 201" - How Vacuum Tubes Really Work

Keith,

Since it's loose from ground, and no corcuit can be made, it hangs in space,
and can only be acted upon by the electron flow from the cathode. In this
case, if the grid is slightly more positive, it will accept some electrons
thus bringing it to 0 volts or slightly negative to ground. This is called
coming into equilibrium or equalling out. If the tube is not slightly
positive, it will not accept any electrons, and the electron flow will be
opposed by the grid. Terman, and I think the author of Tubes 201 discuss
this. In any case, the grid can never be made positive by these actions
taking place.

Earlier, when Rich mentioned about grids, I thought he meant a grid becoming
positive. Bill posted what he meant which is correct and the same as above.
I privately told Rich of this, and am sorry I questioned him, it was a
mis-understanding. We actually were meaning the same thing at the time. Rich
like me does not believe a grid can become positive by being bombarded by
electrons. Even if a grid gets to the point of emitting electrons from being
hot, they are replaced by the electron flow from the cathode. By reading
some other texts, none of those do either.

Best,

Will

*********** REPLY SEPARATOR  ***********

On 7/24/06 at 9:15 PM Keith Dutson wrote:

>I am totally lost on this excessive grid current discussion.  If there 
>is a resistor or fuse tied between the grid and chassis and it blows, 
>the grid obviously has a potential above or below ground.  Which is it?  
>Can it be either depending on the fault?
>
>73, Keith NM5G
[snip]