"Gimmick" capacitors are only good for a few pf, and are
used to do light coupling or introduce
feedback/self-oscillation. even if you could build one, it
would be pretty unstable for test use. *220 pf is
substantial (an air capacitor would have many plates). *In
the day, we'd use silver-mica type capacitors for stability.
* If other friends' junque boxes are available, I'd try
those. *Thank goodness for modern meters--at my age, reading
the color codes is hard!
--W9NPI

Yes, the more I have lookad at it 220 pf would be too large for a
gimmick. I will keep digging in the junque box, maybe find a few other
values to series or parallel to get close to 220 pf.
thanks, w5kcm