[time-nuts] Quick check of a GPS controller oscillator

[Dana Whitlow]

Is the ProgRock GPS disciplined or a Rb, or is it just a free-running
crystal oscillator?
And does LH say that the Trimble is locked OK?

Unless the PrgRock is GPS disciplined (or is a Rb), it's a pretty safe bet
that it has simply grown old
and the crystal has aged.  And this notion is much strengthened if LH gives
a positive indication
that your Trimble is locked OK.

Dana


On Tue, May 5, 2020 at 7:17 PM Giuseppe Marullo <giuseppe at marullo.it> wrote:

> Hi,
>
> I have a ProgRock oscillator that generates 10MHz and 125MHz signals.
> Checking with my Trimble the ProgRock 10MHz signal is consistently below
> 2.5Hz compared to the Trimble and also the 125MHz is below about 24Hz.
>
> My setup:
>
> - Simmetricon time antenna (26dB gain) in clear view
> - about 10m of RG8X cable
> - Trimble GPS (chinese reboxed)
> - Racal Dana 1998 frequency counter with Trimble as time base
>
> DUT
> - Progrock (https://www.qrp-labs.com/progrock.html) with
> - ovenized oscillator (https://www.qrp-labs.com/ocxokit.html)
> - GPSQ board (https://www.qrp-labs.com/qlg1.html) outside on the
> balcony, first floor facing south (almost clear view except North of
> course). connection is made using rs232 cable (about 6m)
>
> I tested for harmonics on my FT857D and Argo, every odd harmonic the
> error increase. The radio has high stability but it is not exact for
> sure. I could test harmonics with my SA but Trimble would be my only
> reference.
>
> The question is: how could I be 100% sure that the Trimble frequency is
> absolutely trustworthy? I have LH and it says oscillator is within
> 300-1000ppt.
> Is it enough to conclude the frequency is okay and the ProgRock is wrong?
>
> TIA
>
> Giuseppe Marullo
> IW2JWW - JN45RQ
>
>
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