Hey group,

Got a few questions concerning the fabrication of an antenna tuner.

I am using Arnie Coro of DX Unlimited's instructions for a simple PI
network tuner.

http://www.radiohc.org/Distributions.../pi-tuner1.htm

Instead of a 10 position switch I am using a 2 pole 6 position switch
then fliping a toggle to use the other 6 positions for a total of 12
inductance settings. But thats not my question.

My question is:

Given the small size of the box this all is going to fit into, I would
like to use a torroidal core instead of an air core.

1) Does Radio Shack sell torroidial cores?

2) Would I wind it similarly to the air core in that each winding is
separated by one wire width and tapped every 3rd turn?

If I understand the concept correctly, it's seems the PI network tuner
tunes both ends of the equation. This would be good as I am using a
Sony ICF-SW7600GR and dont have a clue what the input impedance might
be.

3) Is that how it really works? Tuning both the antenna and the line
out to the receiver?

Arnie says this tuner will work down to 5kHz. And given my research of
this tuner type, I would need to switch in extra capacitance to get
down low for say the AM band. I am considering adding in a few more
toggles to achieve this. My variables are 365pf.

4)How much extra capacitance would be needed? And would this be
practical or should I switch in another inductor creating a PI-L?


Thanks in advance,

Mike