This morning I put together the Pierce oscillator circuit, it took ages to find an RF choke of about the right value in my spares box, I stuck a bit of ferrite up it to help take the value to 2.5mH.
It worked quite well for testing some crystals I had previously salvaged from old equipment..
Most crystals tested OK, coming up very close to their marked value. (probably the meter out by a bit)
6.144 MHz
6.250 MHz
4.000 MHz
But a couple were different.
This one marked as 40.000 was coming up as 13.33MHz
And this one marked as 3.2768 was randomly coming up as two different values 9.644 MHz and 3.277 MHz.
This one and another like it marked as 21.8MHz sold to me some time ago for a pantry TX did not seem to work at all.
The display on the meter was changing all the time.
Has anyone got explanations for the ones with odd readings?
Do you think the large 21.8MHz crystal would work in another circuit?
thanks
Mike
It worked quite well for testing some crystals I had previously salvaged from old equipment..
Most crystals tested OK, coming up very close to their marked value. (probably the meter out by a bit)
6.144 MHz
6.250 MHz
4.000 MHz
But a couple were different.
This one marked as 40.000 was coming up as 13.33MHz
And this one marked as 3.2768 was randomly coming up as two different values 9.644 MHz and 3.277 MHz.
This one and another like it marked as 21.8MHz sold to me some time ago for a pantry TX did not seem to work at all.
The display on the meter was changing all the time.
Has anyone got explanations for the ones with odd readings?
Do you think the large 21.8MHz crystal would work in another circuit?
thanks
Mike
