Mark to my inexpert eye that doesnt look like a very good overtone oscillator but I appreciate that it is slimmed down to keep the weight and size down, I can see why it is touchy. There is nothing to make the oscillator degenerate at the crystal fundamental. In fact it looks like a Pierce with a tuned circuit in the anode. If it goes off at the overtone my guess is that it by luck! But there are more clever people than me in this Group who may be more useful to you.
Old fashioned crystals (lapped to frequency) used 5th OT up to just over 100MHz and the 7th and then 9th the blank was too fragile to go further. I believe modern micro machining techniqes where a thicker ring of quartz surrounds the resonator will allow a 5th overtone operation at 200MHz but you still have to make sure it doesnt go off at the fundamental or the 3rd .....it may still transmit, but it will be off-channel and lower in power. Overtones are not harmonics.....in radio anyway. Alan G3NYK ----- Original Message ----- From: "Mark Sims" <hol...@hotmail.com> To: <time-nuts@febo.com> Sent: Thursday, September 30, 2010 7:57 PM Subject: [time-nuts] Small quantity custom crystals I need to build some small tracking transmitters (using a circuit similar to http://www.jbgizmo.com/page4.html This circuit uses a fifth overtone crystal to get an output in the 216 to 220 MHz range. The circuit is rather finicky about the crystal and transistor... most don't work. Smaller and more rugged crystals are preferred. Does anybody know of a place that can make 1 off crystals in this range for a reasonable price. Many of usual suspects don't seem to be able to make crystals in that range. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.