PaoloC wrote in message ...
Hi.
I have spent part of the weekend trying to resonate al old CB XTAL at
its fundamental frequency.


need the same if I want the fundamental?

Are overtone XTALs "harder" to resonate?

Are those old CB XTALs 3rd overtone?

I assume my 27MHz XTAL works. :-) Thanks in advance for all suggestions,
Paolo IK1ZYW
Yup They are 3rd overtone. Try a little series inductance with the
rock, and maybe a few pf of capacitance in parallel. I seem to
remember these being cut for a 25 pf load versus the more common 330
or 32 pf load of fundamental rocks, but the rock may also be defective
(I've seen quite a few) Good luck, Mike.