"mrhaney" wrote in message
oups.com...
I have about 60 military crystals ..they are marked Channel 277 thru CH
347 .Anyone know if they are overtone ,and, know of a good way to
check them.. My grid dipper will not oscillate with them like it does
with basic fundamental crystals ,like 7193 KHZ. etc..THEY ARE FOR
SALE TOO..W4PQW


Mr. Haney,

All crystals will operate on their fundamental as well as the overtone
modes. Too bad they aren't working in your g-dipper. What holder are they
in? Is it the old standard FT 243 (if I recall the number correctly).
Channel numbers could be for anything. A simple Colpitts osc could be built
to see where the fundamental is.

Use the SECOND circuit he
http://hem.passagen.se/communication/txo.html
Use both 150 Pf. The total of C3 and VC1 can be around 50-100 pf and it
should oscillate so you can measure / count the freq. R3 = 2.2K should get
it going.
73, Steve, K9DCI