[time-nuts] Good GPSDO on eBay?

[Michael Wouters]

"Full tested by Agilent 53132A with US-012 option and Ex-ref from
trimble thunderbolt
GPSDO."

I think what the seller saying is that the counter was externally
referenced to the Thunderbolt for the frequency measurements that they
state.

Cheers
Michael

On Sun, Jul 10, 2016 at 10:58 AM, Charles Steinmetz
<csteinmetz at yandex.com> wrote:
> Richard wrote:
>
>> This looks like a good beginner's GPSDO on eBay: 172148560746
>>
>> "This is GPS Disciplined Clock made with trimble GPSDO Board.Full tested
>> by Agilent 53132A with US-012 option and Ex-ref from trimble thunderbolt
>> GPSDO."
>>
>>       The seller says it has a sine wave output and is accurate from
>>       10e-11 to 10e-12.
>>
>> Any thoughts?
>
>
> It is very hard to say exactly what you will get, because the seller (who
> uses a dozen or more different ebay IDs) seems to change the design every
> time the wind shifts.  But typically they are FLLs (frequency locked loops),
> not genuine PLLs (phase locked loops), and have a small frequency offset
> because the design does not address some systemic issues of FLL design.  It
> is unlikely to deliver better than 10e-11 performance with any certainty.
>
> In addition to that, if  "Ex-ref from trimble thunderbolt GPSDO" is supposed
> to make a buyer think it will have the best Trimble OCXO (P/N 37265), the
> one that was in the Trimble Thunderbolts of list legend, that is almost
> certainly false.  It may have a Trimble-branded OCXO, but even if it does it
> will be one of the many lesser part numbers.
>
> To me, the attempts to mislead buyers is enough, by itself,  to rule out
> dealing with that seller, under any of his ebay IDs.
>
> Best regards,
>
> Charles
>
>
>
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