Keith,
Excessive grid current did, either from being over driven, or an arc from a
gassy tube.
Best,
Will
*********** REPLY SEPARATOR ***********
On 7/24/06 at 10:28 PM Keith Dutson wrote:
>I am not talking about AFTER the fuse blows. What current CAUSED it to
>blow?
>
>Thanks.
>
>Keith
>
>-----Original Message-----
>From: amps-bounces@contesting.com [mailto:amps-bounces@contesting.com] On
>Behalf Of Will Matney
>Sent: Monday, July 24, 2006 9:33 PM
>To: amps@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]
>
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