[BC] Harris FM10 250 driver

[RichardBJohnson at comcast.net]

It is not impossible. You can convert the input to 50 ohms with a simple circuit.

(1)	You use the IPA components to form a parallel resonant tuned-circuit with the input of the tube you want to drive.
(2)	You install a Type "N" connector somewhere close to take your RF input power.
(3)	You connect the center of the connector to a small piston trimmer capacitor of between 5 and 25 pF with the other end going to the "hot" side, the side closest the tube to be driven, of your parallel tuned circuit.

Using a source of RF power at your frequency, and a thru-line reflected power meter, adjust the parallel tuned circuit and the small piston capacitor to minimum reflected power when the driven tube is operating.

If the tube has so much input capacity that one cannot reasonably make a parallel-tuned circuit, rearrange the components to make it a series-tuned circuit.

Cheers,
Richard B. Johnson
Book: http://www.AbominableFirebug.com/

----- Original Message -----
From: "Jim Offerdahl" <jim at offerdahlbroadcast.com>

First of all, I erred in my first post, we are using the 4CX300 in this 
box. I have been told that it is not 50 ohms in and out and that's what 
makes it difficult if not impossible to upgrade to SS.