[Amps] Grid fuses (was: Life and gain of 3-500Z)

[Bill Turner]

ORIGINAL MESSAGE:

On Fri, 21 Jul 2006 04:31:23 -0700, Richard wrote:

>Why doesn't the effect of arriving electrons take the grid in the  
>negative direction?


------------ REPLY SEPARATOR ------------

I assume you are asking the question rhetorically, but the answer is
that it does indeed take the grid negative.

To prove this, just float the grid and connect a high impedance
voltmeter between grid and cathode. With only filament/heater power
applied, the grid will show a few volts negative, with the exact
amount depending on the design of the tube. This voltage will appear
even with no anode voltage at all. I've done it many times with small
receiving tubes, although not with transmitting types.

Again, I don't recommend this as a method of bias because there is too
much possible variation between tubes, even of the same type. It's
just an interesting experiment.

Bill, W6WRT