[time-nuts] GPS Referenced Programmable Oscillator...

[Attila Kinali]

On Sun, 18 Oct 2015 17:56:36 -0700
"Burt I. Weiner" <biwa at att.net> wrote:

> I just ran across this and wonder what you think.
> 
> http://www.force12inc.com/products/gps-locked-precision-frequency-reference-low-jitter-gps-clock-450-hz-to-800-mhz-output.html
> 
> Seems like it could be set up as a reference to replace crystals in 
> some Ham rigs such as a repeater transmitter and receiver.


I've seen this being mentioned a couple of times in the past weeks.
The phase noise looks ok'ish. Not great, but not too bad either.
Though I doubt that he'll be much below the noise floor of his instrument.
140dBc is about what you get with most VCXO/TCXOs. To be better you
need to know what you are doing and/or use a good oscillator, which
becomes expensive (a good, low noise VCXO costs already 100USD
in small volumes unless you build it with discrete components,
which then takes considerable knowledge).

An ADEV plot and any kind of schematics are missing completely.
Also without any reference, I would distrust the way how the
system is build. There are ways how people trying to do the right
thing will mess up in subtle ways. (e.g. like using an FLL instead
of a true PLL, as is the case for the BG7TBL GPSDO)

For 200EUR, it's also on the expensive side, if you compare it with
what you can get on ebay. Of course, there is the difference between
a used device and a new device.

On a personal note, the product description reads too much like
"hey, the guy who designed this is really really great!"
I am not sure what I should make of that, but I don't think that's
a positive attribute.

In summary, I'd probably wait for a time-nuts to get his hands on this
litte gadget and do some serious measurements before I'd trust it.

			Attila Kinali
-- 
It is upon moral qualities that a society is ultimately founded. All 
the prosperity and technological sophistication in the world is of no 
use without that foundation.
                 -- Miss Matheson, The Diamond Age, Neil Stephenson