[Amps] grid resonance

[Steve Thompson]

Tom W8JI wrote:

> If you apply a leveled source to the cathode (and don't have 
> any resonant systems connected to the cathode) and measure 
> the output voltage passed through to the anode, you actually 
> can determine the frequency where the grid is parallel 
> resonant (high impedance). There is a sharp peak in 
> feedthrough because the grid is no longer grounded. 
> Somewhere about that frequency is where the tube goes into 
> parasitic oscillation.
> 
> If there is enough interest, I can sweep several tube types 
> and show the difference.
I'd be interested - it's valuable info and I'd like to see how someone 
else's tests compare with what I got last year: 
http://lists.contesting.com/archives//html/Amps/2005-04/msg00153.html

Steve