[Amps] RCA load impedance calculation

[Xmitters at aol.com]

In a message dated 4/10/06 6:29:04 PM Central Daylight Time, 
amps-request at contesting.com writes:

<< Gerald,
 
 I went ahead and brought the RCA transmitting tube manual TT-5 here to quote 
what it says.
 
 Effective RF load resistance;
 
 2 x (Eb - Ebmin) / Ibo
 
 Ibo = Zero signal plate current
 
 "Ibo should be between 1/6 and 1/10 of Ibmax found on the typical plate 
characteristics graph".
 
 "Determine peak plate current (Ibmax) for zero bias (Ec1 = 0) at or slightly 
below the knee of the zero-bias curve for the value of Ec2". 
 
  >>

Hello:

I'm looking at my copy of the RCA Transmitting Tubes book, TT-5 page 53 
equation 15.

RF Load impedance is = 2 * ( Eb- ebmin)/ Ibmax   (Ibmax not Ibo )

Maybe there is a mis-print in your book. It is also hard to read. So using my 
example numbers in my original post for a class B:

Rload = 2 * (3000-300)/1 = 5400 Ohms

Ibo is the idling plate current with no signal, and I don't see how that 
would be an appropriate parameter for calculating the required load resistance the 
tube wants to see.

Jeff Glass