[time-nuts] New pics of RFTG-m-Rb, and some comparison details

Jason Rabel jason at extremeoverclocking.com
Sun Dec 31 22:08:46 EST 2006


David,

Your thinking pretty much along the same lines as me from your post.

FYI, I didn't mean the XO itself, I meant the "XO module" (specifically the
GPS/PPS signal).

There is also a "RFTG-u REF 0" on eBay, however the picture is so poor I
can't make out all the connections. But it too has the alarm, 24V,
Interface, RS-485/1PPS, and a pair of SMA connections. It has one additional
DB9 connection (that I can't read, I think it might be another Interface).
The function of the unit itself is unimportant, but this just illustrates
the system is modular and probably signaling between modules is very basic
since they are all the same size / connections.

I agree with you that the RB has to be disciplined / adjusted somehow, and
not by opening the chassis. Just from the design of the shell it is obvious
that it is not meant to be opened regularly, definitely not in the field,
and there is no easy access to the RB adjustment screw (especially if the
unit was in the open-frame chassis and powered on).

BTW, did anyone else's RFTG smell like a stinky old sock, or a gym locker
room? Pee-yew!

Happy New Year everyone, this is going to be my last post for the year. :)

Jason


> 	So the logical thing to do is use a rubidium reference which can
> very easily have less than one part in 10^11 drift per day 
> and typically
> much better than that.   This gives much more time to repair, 
> and if the
> Rb is doing well that may extend into several days or even a week or
> more.  Enough time to get to the site and fix the antenna, cables,
> etc...
> 
> 	But obviously the only way the Rb is useful is if it is
> disciplined somehow so it starts out dead on.   Relying on 
> the factory C
> field setting to be within parts in 10^11 years later is ridiculous
> considering variations in local magnetic field, aging etc... it is
> probably not possible to do much better than parts in 10^9 in 
> a factory
> shipped without field adjustment situation in fact.





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