[time-nuts] A couple of Tbolt questions

John Miles jmiles at pop.net
Thu Jul 23 16:29:46 UTC 2009


> Didn't that older unit use a different oscillator anyway?

Yes.  Its broadband PN wasn't that bad, but it wasn't very clean/stable at
short timescales.

Further complicating matters is that my old Thunderbolt probably had 10,000
or more hours on it before I ever even gained the ability to measure its
phase noise.  Maybe it was better when it was brand new, and maybe the TAPR
units will be noisier after 10,000 hours.  Age doesn't have much effect on
PN in my experience, but that experience is still rather limited.

> I seem to remember from your web page notes that it used a Piezo
> oscillator
>  but any I've seen since, whether firmware version 2.2 or 3.0 and
> including TAPR units and units from two Chinese sources a couple
> of years  apart,
> have used the Trimble 37265 oscillator.
>
> Perhaps the Trimble oscillator is generally cleaner than the
> Piezo one by
> default?

That's what I've been assuming all along, but the idea that some of them
were hand-selected for PN is new to me.

-- john, KE5FX






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