Hi Fred:

Many receivers capacitors have the outside plates separated into sections,
like a pie. This is for the purpose of calibrating the receiver to the
dial. But carefully moving the plates, excellent calibration can be
achieved.

It requires a bit of logic and patience. Find out the frequency range of
the vfo (not the output frequency). The simples approach is to put a
frequency counter on the output. Then, note the calibrated frequency to the
actual frequency. Let is say at the 100 kHz range, the dial reads 100, but
the actual frequency is 103. That means the vfo is 3 kHz high, which means
not sufficient capacitance at that point. I would draw a correction graph
for the entire range.

You know that at 100, you need more capacitance, bend the plate in a bit at
that point where the rotor is just meshing with the stator. A little bit at
a time.

Note that not all capacitor plates are designed to be bent like that.
Generally, the high precision variable capacitors are not designed to be
adjusted by moving the plates.

It is 1/2 science and 1/2 art.

Once you get the hang of it, you can use a small file and file a little
notch off at any point to make fine corrections. Warning, do not do this
without thought first, or you will make things irreversibly worse and we
will see it on eBay.

73, Colin K7FM