I am in the process of designing an ATU yet am having difficulty in locating
a company who can supply a suitable Variable Capacitor.

At the moment the only ones I seem to find are trimming capacitors and I
require an item which is somwhat larger than that - E.g in the region of
about 680pF.

Any suggestions as to a suitable supplier would be grately appreciated.

Failing this if anyone knows of a circuit diagram available on the net which
may be constructed from components more readily available then I am more
than happy to hear from you.

Many Thanks.