[time-nuts] Mechanical 1PPS Oscillator Disciplining
kb8tq at n1k.org
Sat Jan 10 10:19:23 EST 2015
The speed of sound in quartz varies by axis, but only by about 2:1. The same basic physics that gets you a fundamental 5 MHz crystal that is at thickness Z gives you some dimension on a 5 KHz crystal that’s close to 1000 * Z. Very low frequency crystals pretty much have to be designed so they resonate on a “long” axis of the blank. If they don’t then the blank / enclosure / price gets crazy big.
If you want to calculate just how long this or that resonance might be:
Has all the numbers you would need.
> On Jan 10, 2015, at 2:06 AM, David J Taylor <david-taylor at blueyonder.co.uk> wrote:
> Hi Tom dividing down wasn't always necessary I have sample from the UK GPO
> Crystal Factory of NT-cut bars, quartz tuning fork, and Gapped Ring
> crystals, the latter marked 400cps (pre Hertz :-)) ) I think these are
> post WWII because they are mounted in IO base GT style tube envelopes.
> Dividers were achieved with neons and locked multivibrators, where
> necessary, I believe.
> I have one "500 c/s" GEC crystal in an octal base which is thinner than a "60 Kc/s" one, so a different mode. Never had it working, though.
> David GM8ARV
> SatSignal Software - Quality software written to your requirements
> Web: http://www.satsignal.eu
> Email: david-taylor at blueyonder.co.uk
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
More information about the time-nuts