[ARC5] Plate impedance...

[Roy Morgan]

On Dec 14, 2008, at 11:02 PM, WA5CAB at cs.com wrote:

> 550/0.150 = 3666.67 ohms.  Call it 3.5K.

I think Bob left out a two.

From:

RCA Ham Tips
Vol. 14 No. 2
July-August 1954
Components for Pi-Coupled Amplifiers

"The exact load for tubes not listed in Table I can be determined from  
a set of complicated calculations.   However,a good approximation can  
be made with the formula:

Estimated Plate Load (ohms) = Eb/2Ib  "

E sub-b divided by (two times I sub b)

That "half plate voltage divided by plate current" is familiar from a  
session trying to puzzle out why a Johnson Desk Kilowatt did not  
modulate properly.  We were figuring turns ratios and the like. (It  
was the mod transformer that needed to be rewound.)

Roy

Roy Morgan
k1lky at earthlink.net
529 Cobb St.
Groton NY, 13073