Your first osc got an overtone and the second the fundamental of 9 MHz and
the the 3rd overtone is 27MHz. It could also be a lower frequency like 3 or
1.5 MHz so listen for these frequencies. The 3rd or other overtones are
slightly higher than an odd multiple of the fundamental!
hank wd5jfr
"Uwe Langmesser" wrote in message
...
I have an unknown crystal I wanted to test for its frequency.

On qsl net I found a test circuit to do just that (I think it is basically
a
broadband amp).
Initially when I hocked the circuit up on my breadboard the crystal seemed
to oscillate at around 27 MHZ.
Then I built the little circuit on a permanent board and now the crystal
oscillates at about 9 MHZ and at this point I start to ask myself what am
I
measuring here. And what assures me that 9 MHZ is the fundamental?

I would appreciate if anybody could shed some light on crystal testing.

Uwe