Hello,
Should the SWR reading be considered when the impedance reads 50 Ohms
looking into the output of a Pi-L circuit?
The question came about when trying to checkout a Pi-L circuit installed in
a homemade amp. The set-up:
* An Autek RF-1 is used to adjust the load capacitor (C2) to the
calculated value at the checkout frequency while C2 is disconnected from
the circuit.
* A resistor (carbon composition) for the RL value with a capacitor
(silver mica) representing the tube's output capacitance connected in
parallel are connected from the anode lead to ground with the tube removed.
* With C2 reconnected to the circuit, the Autek is attached to the
circuits output.
* Tune capacitor (C1) adjusted to give a 50 Ohm impedance reading on
the Autek. Note: The physical spacing between C1's stator and rotor seem
to be in the proper range for the frequency. (C1 is a Jennings UCS 400
which makes it easy to see the position of the moveable part, the so called
rotor, in relation to the fixed part, the stator.)
However, the SWR reading is out of range of the Autek. Made the same
measurement at the circuit's output using a MFJ259 and got the same results.
Want to insure the Pi-L circuit is capable of functioning properly before
power is applied.
73,
Mike, K4GMH
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