[AMPS] Resonances

[Tom Rauch]

> Date:          Thu, 14 May 1998 22:11:44 +0100
> From:          Steve Thompson <amps@txrx.demon.co.uk>
> Subject:       [AMPS] Resonances

> I measured between the rear centre bearing and one of the corner bolts
> of the stator rail, frequency range 10-300MHz.

Bolt it to a groundplane, and measure the connection with the 
shortest lead possible. In my test, I measured the actual component 
used in its operating location. 

If you measure a typical tuning cap made by All Star or Cardwell, 
you will find it is virtually impossible to cause the plate tuning 
capacitor commonly used in domestic PA's to arc at VHF.

> I added a few inches of thick wire to simulate the anode to capacitor
> lead and then, looking at it from the anode's point of view, both series
> and parallel resonances ('short' and 'open' circuit respectively) went
> down in frequency a bit.

You really should measure impedances in actual system with the layout 
and components used if you want to determine possible VHF voltages.

It's very easy to measure voltage by driving the anode with a known 
RF voltage and measuring the voltages in the tank.

73, Tom W8JI
w8ji.tom@MCIONE.com

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