[time-nuts] AM vs PM noise of signal sources
Charles Steinmetz
csteinmetz at yandex.com
Tue Jan 9 12:36:31 UTC 2018
Bill wrote:
> A switching regulator without the steep (and noisy) transients of
> today's switchers.
Well, don't get too giddy about how quiet the scheme is <smile>. HP
warned that if you use the same 12v (nominal) power supply for the oven
control and crystal oscillator circuits, you need to add extra filtering
to the oscillator power line to avoid injecting switching noise into the
sensitive oscillator circuitry.
I always use separate voltage regulators for the oven control and
crystal oscillator circuits when I build a 10544 or 10811 into a
project, and I have modified HP instruments by adding an additional
regulator for the oscillator section when they had 10544s installed, to
good effect. Even then, a small amount of switching noise is induced
into the oscillator section internally to the 10544.
That said, it is a simple and robust system that performs quite well in
general.
Best regards,
Charles
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