[time-nuts] Small quantity custom crystals

Richard (Rick) Karlquist richard at karlquist.com
Fri Oct 1 17:23:40 UTC 2010

On 9/30/2010 12:43 PM, Alan Melia wrote:
> 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.

I agree completely.  What I have found to work is:

Build a free running Colpitts oscillator and get it tuned to the
frequency you want.  Then, insert the crystal in series with the
emitter.  Insert the load in series with the collector.  Obviously,
this is easiest if a "grounded collector" topology is used.  I used this 
for many high volume crystal oscillators and they just worked, period. 
No tweaking.

Rick Karlquist N6RK

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