[AMPS] Pi-L networks

[Peter Chadwick]

Does anyone have any comments about the Q of the L network section in Pi-L
networks? I have seen it suggested that the impedance at the middle of the 
pi-L should be the geometric mean of the input and output impedances:  the Q
of the L will then be given by

Q = sq.rt.(Ri - Rl)/Rl

where Ri is the intermediate impedance in the Pi-L (i.e. the geometric mean)
and Rl is the load impedance (usually 50 ohms)

For an 1800ohm plate load, this gives a Q of 5 for the L section, which
appears to be the right order of magnitude.

Of course, the Pi section would run at the usual Q - 10 to 15, or so.

Comments, please?

73

Peter G3RZP

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