[time-nuts] Practical considerations making a lab standard with an LTE lite

Dave Martindale dave.martindale at gmail.com
Sun Nov 23 14:26:13 EST 2014

Did you use one-ply, two-ply, or three-ply TP?

More seriously, your LTE-Lite differs in a couple of respects from the
batch of "production" ones, or at least my example.  Your TCXO seems to be
in a metal package (shiny gold colour) and open to the air, if I'm
interpreting the photo on your LTE-Lite page correctly (and also the photo
that Said posted in his divide-by-two document).  The production units have
the TCXO in a solid black package, probably black epoxy, with a blob of RTV
rubber on top.  So the "production" units are probably already somewhat
better shielded against drafts.

(Thanks for doing the tests, particularly for those of us who can't do
these tests ourselves.  I can only watch the 1 PPS of the LTE-Lite wander
with respect to the 1 PPS from my old Thunderbolt (Piezo oscillator), and
look at the worst-case variation, but I have no way of knowing how much of
the drift is due to each GPSDO).

- Dave

On Sun, Nov 23, 2014 at 11:24 AM, Tom Van Baak <tvb at leapsecond.com> wrote:

> The short-term performance is 10x worse if you don't shield the TCXO from
> air, even if the ambient air is "still". I suggested Said sell the product
> with some sort of engineered shield in place. Instead each of us will solve
> the problem in our own way; which is ok for a dev kit.
> For plots and photos showing performance with, and without, and with
> insulation see:
> http://leapsecond.com/pages/LTE-Lite/
> The difference is dramatic, especially if you are used to working with
> OCXO where this sort of effect does not occur.
> The insulation may be found in convenient rolls at many local stores. I
> used TP, which for this application is an acronym for Thermal Paper.
> /tvb
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