[time-nuts] Small quantity custom crystals
alan.melia at btinternet.com
Thu Sep 30 19:43:06 UTC 2010
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.
----- Original Message -----
From: "Mark Sims" <holrum at hotmail.com>
To: <time-nuts at 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
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 at febo.com
To unsubscribe, go to
and follow the instructions there.
More information about the time-nuts