I would like to check the frequency of 35Mhz Radio Control receiver
crystals, using the Weedtech / Peter Cousens Frequency meter. I've built the
meter and it's now working fine, but when I try to measure the frequency of
RC crystals driven using a Colpitts oscillator, I only read around 11.5Mhz.
If I substitute a 'normal' crystal, say 20Mhz, it works fine.

What am I doing wrong?

Is it an oddity of the type of crystal, or is it just me?
Would be grateful for any light anyone can shed on this.

Cheers,
Andy Holdaway