[time-nuts] Fix Trimble Oscillator??

John Miles jmiles at pop.net
Fri Apr 22 08:34:44 UTC 2011


> jmiles at pop.net said:
> > I can confirm that the whole oscillator including oven runs on 12 volts.
> > However, you do have to connect two different pins to +12 and
> two different
> > pins to ground to make it work (see attached).  ...
>
> Nice pictures/graphs.  Thanks.
>
> What's the spike at 60KHz?

No telling, probably leakage from a switching regulator somewhere.

Spurs under -150 dBc/Hz are elusive enough to track down, and once you get
down below -160 it's often impossible to observe them from one measurement
to the next.  Digital analyzers like the TSC5120A attempt to remove their
own spurs from the measurement, but this process isn't always perfect.  The
only sane approach is to ignore low-level spurs unless/until they are
associated with specific problems.  (An actual defect in the oscillator will
usually show up at well over -140 dBc/Hz.)

> There is another one at a bit under 200 KHz.

200 Hz?  That'll be the third harmonic of 60 Hz.  Again not worth sweating.

-- john, KE5FX




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