[time-nuts] Where to get Winchester connections for Efratom FRK?

Rex rexa at sonic.net
Fri Nov 23 03:41:07 EST 2007


swingbyte wrote:
> As an aside, what resolution counter is needed to calibrate the FRK?  Hp 
> 5328? HP 5370?
>
>   
That's kind of an open-ended question. You don't actually need a 
counter, you need a source that is known to be at least as accurate as 
you want to set the FRK. One question is: do you really have a need for 
a level of accuracy that you are trying to work toward? The group, in 
general, tries to go towards "because it is there" challenges in 
accuracy, stability, and phase noise. It isn't required by everyone.

When I got my FRK working I used a LORAN receiver to tweak the FRK over 
a period of several days. Even though the xtal oscillator in the FRK had 
aged to the point that the unit wouldn't lock when I got it, after the 
fix for that and oscillator centering to the Rb source, the whole unit 
was not very far off from LORAN. The Rb is not a primary standard, so it 
does need to be calibrated periodically to maintain frequency accuracy, 
but it should be very close for a long time.

I would not expect that any, even good, OCXO based counter that you 
might pick up could be used by itself to calibrate your Rb source. You 
need something like a Cs based standard, a LORAN timing receiver, or a 
GPS based timing receiver (the most common for all but the highest 
requirements these days) to use as a reference.

I think I saw that you are in AUS somewhere. Maybe if you post where you 
are, someone in the group will volunteer to help you get started in 
calibration and general knowledge.

These questions come up a lot in this group. There has been a discussion 
that maybe there should be a repository for the group with a FAQ, some 
tutorials or discussion captures, and collected documents. Lots of 
members have portions of this available on their pages. Anyone willing 
to start work on a FAQ? I have some web space too and could help, but 
others here have already done more to collect and share this knowledge 
than me and know more than I have tried to really understand.






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