I need to be able to vary the capacitance of tuning capacitor for a [huge] ferrite antenna from 3 pF to 0.3 uF -- a range of five orders of magnitude.
It does not appear that there is an air variable cap that can do the job, at least one smaller than my house.
I was thinking of using 18 or so fixed caps each with an SPST switch to include or exclude each one, with the first being 3pF, the second being 6pF, the third being 12pf, etc. -- like a binary number. Then I could set any capacitance in the range to within 3 pF.
Since SPST switches are around 70 cents, I was instead going to use a18-pin strip double pin pin-header strip ($2.04 at Mouser) and 18 shunts (15 cents per) to switch each cap.
Is there a better way of doing this?
Ken (to reply via email remove "zz" from address)