"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

In article ,
w5kcm wrote:

"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. =A0220 pf is
substantial (an air capacitor would have many plates). =A0In
the day, we'd use silver-mica type capacitors for stability.
=A0 If other friends' junque boxes are available, I'd try
those. =A0Thank goodness for modern meters--at my age, reading
the color codes is hard!

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.

Gimmick caps in that range are probably made from sheet metal cut out of
tin cans. I find Altoids tins work well.

Use a cheap DMM with a capacitance function to measure them... then cut
them down until the value is correct.
--scott
--
"C'est un Nagra. C'est suisse, et tres, tres precis."

On Feb 14, 10:39*am, w5kcm wrote:
"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

OK, last night I found another stash with some capacitors and found a
couple small 200 pf silver micas in there. That should work. Thanks
for all the input. Not sure about the Jack Benny, that one sailed
right over.
73, Randy