The S and Z Match for the URAT

I was going to disassemble the u.RAT and re-use the components, but I have just come into a second variable capacitor – which is the Palstar C600, a true work of art. I am trying to get rid of having a roller inductor in the circuit, but would much rather have a switched inductor. Yesterday I posted this circuit:

And the Palstar BT1500A has this circuit:

Pas, PE4BAS, alerted me to PA0FRI’s wonderful web site (thanks Bas!):

And his S Match circuit:

I also found Phil, AD5X’s Z Match project:

What is really fantastic is how I will be able to use the URAT, and either use a switched tapped inductor, or maybe just have two variable capacitors under URAT control. I don’t have the heart to mangle the Palstar BT1500A and make heavy modifications by adding relays to its switching circuit.

The URAT spins the variable capacitors at the right speed with the Elecraft KPOD, and while the NEMA-23 steppers are more than adequate for the variable inductor, its too slow to tune with the KPOD.

If I can get one of these circuits to tune on 160, 80 and 30M with only two variable capacitors and an “auto transformer” or single tapped inductor, I will be “in like Flynn” . . .

Stay tuned, we have a three day weekend, and I will be experimenting when its not too hot out (we have predictions for 43 C / 110 F heat wave today and tomorrow). I might get lucky and have Sunday and Monday in the morning to play with this.


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