Need help with values of Pi-network for tank

Jim Bowman jimbowman at SEANET.COM
Mon Nov 22 01:39:22 EST 1999

Hi to Lane and the List. I don't have a computer program for that, but
unless I screwed up, these are the approximate values I came up with using
the handbook and a calculator and some charts. I have a publication
somewhere (old) on this very subject. Will see if I can come up with it.

Anyway, you have to make some assumptions, and I assumed about 52 ohms load
on the output, and a Q of 15, which seemed to be kinda middle of the road. I
used your value of 6000 ohms input load.

The reactance of the input cap will be about 400 ohms, and the reactance of
the output cap will be about 50 ohms, and the coil reactance will be about
440 ohms. If that is correct, I get the following approximate values for the
components (the value of the output cap for 160 meters is very approximate):

Input cap value:              225pF(160M),  110pF(75/80M),  55pF(40M),
Output cap:                    1800pF(160M), 1000pf(75/80M), 450pF(40M),
Tank coil (microhenries)  40uH(160M),    23uH(75/80M),   12uH(40M),

I hope this helps, and I hope I didn't screw it up - this is the first time
I actually sat down and tried to figure it out. Someone double check.


Lane Zeitler wrote:

> if any of you have access to the computer programs is it possible to ask
> what you are coming up with for an RL of 6,000 ohms in a pi-network
> configuration. Looking for the values of Ctune, L, and Cload. primarily
> interested in 160, 80, 75, 40, and 20 meters.
> Lane
> Ku7i
> San Diego

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