[Amps] High C out

[Dennis12Amplify at aol.com]

In a message dated 1/21/05 12:49:50 PM Central Standard Time,  
vic at rakefet.com writes:

Nope,  he's talking about adding some inductance between the plate and the  
tune-C, making a kind of "L-Pi" (or L-Pi-L!) network.  The idea is  that with 
very high plate load impedances it may be impossible to get a  low-enough 
minimum 
capacity in the tune-C to permit a reasonably low  Q.  Adding some inductance 
before the Pi network pre-transforms the  load impedance to a lower value so 
a 
practical capacitor can be  used.



I agree.
 
 He's creating a two stage impedance transformer.
 
 I'm sorry but I consider a Pi network a Pi network no matter which  end is 
connected to where; and I know that the large C is on the low impedance  side 
of the impedance transformer. I did't realize I was in error calling it a  Pi-L 
network instead of an L-Pi network, but I guess I can see where some may  get 
confused. I DID state that the PLATE C became the new TUNE C in  that 
configuration.
 I have used it myself in some cases to UP-CONVERT impedances to  obtain a 
reasonable tank Q.
 A good example being multiple sweep tubes in parallel where the total  plate 
capacitance is greater than 50 PFD. I have also used similar  circuitry to 
match the Collector impedance from the output of a single  ended transistor 
amplifier before we started using broad band transformers to do  the impedance 
matching, but once again that was for converting a low impedance  to a higher one.
 
Dennis O.