[Amps] Plate impedance formula

[Joe Subich, K4IK]

> Will,  For the way the output tank sees it, in a common 2 
> tube amp, would that value double, half, or stay the same? 

As far as the plate tank is concerned, the plate impedance is 
the total plate current (current drawn by both tubes or two 
times the current drawn by a single tube) and the plate voltage
common to both tubes (they are in parallel). 

A single 4CX800 at 2200 volts and 600 mA would represent 
(2000 / 1.8 * .6) or roughly 2000 Ohms.  If you make that 
a pair your plate impedance is about half that (2200 / 
1.8 * 1.2) or about 1000 Ohms.

73, 

   ... Joe, K4IK