[Amps] Re: Rm resistor

[Phil Clements]

Subject: [Amps] Re: Rm resistor


>I had intended to do something similar to this to a new amplifier to
> establish the correct position for the taps on the coils.  I am a 
> little
> puzzled about how to go about it for a Pi-L network.  I plan to use 
> a
> Boonton RX meter to make the measurements.
>
> Since there are two coils to be adjusted, it would seem that first 
> you have
> to set the tap on the Pi coil using the design image impedance and 
> circuit Q
> and the calculated value of tuning capacitor capacitance, then not 
> changing
> the Pi coil and tuning capacitor settings, set the output coil tap 
> using the
> calculated capacitance value for the loading capacitor.
>
> Is there a fallacy in my reasoning or a better way?
>
> David C. Hallam
> KC2JD

The L coil is not that critical, as you can see in the Handbook.
Use 9.4uh, 4.4uh, 2.5uh, 1.25uh, .84uh, and .65uh for 160, 80, 40 20, 
15, and 10m and you will be fine.
Adjust the ball-park value of the pi coil, C1, and C2 to that obtained 
by the chart in the ARRL Handbook.
This will put the Q also in the ball-park to start your testing.

(((73)))
Phil, K5PC