[time-nuts] femtosecond jitter anyone?
Magnus Danielson
magnus at rubidium.dyndns.org
Wed Apr 8 23:07:07 UTC 2009
Bruce Griffiths skrev:
> Magnus
>
> For examples of the use of crystals in filters for cleaning up the
> output of a crystal oscillator look at the circuit schematics for some
> of the early crystal frequency standards.
> Crystal filters were used quite liberally in some of these to clean up
> the outputs.
It's used in the step-up chain of the SR620 for instance. The SR620 has
a 10 MHz oscillator (TCXO or as in my case a Wenzel OCXO) which is
stepped up to 90 MHz using a fairly ordinary odd-order stepup and
filtering chain. The ECL logic counter frontend use this as coarse
counter frequency. The analog interpolators is a bit interesting in a
few peculiarities but nothing really exciting.
The crystal filters of that chain is setup in PI-filter style with the
crystals in serial mode.
> However it may be necessary to control the temperature of these crystals.
Indeed. I wonder if he really needs that level of sine purity. An LC
tank should be sufficient to get started.
Cheers,
Magnus
More information about the Time-nuts_lists.febo.com
mailing list