[time-nuts] FRK-L OK or too tired?

Marco Bruno IK1ODO at spin-it.com
Fri Sep 8 15:14:16 EDT 2006

At 23.31 07/09/2006, you wrote:
>James and Brooke,
>Thanks for the informative replies. I have done pretty much what you
>suggested. The result is a nice sloped line in the positive direction,
>indicating that the FRK-L Rb source is running fast at a rate of about
>I checked the lamp and crystal osc monitors and both are within spec.
>The crystal mon was 5V (2-16V is the suggested range), so I adjusted it
>up to 10V with the range adjust trimmer.
>I don't know if an FRK-L running for 13 years is expected to be 1E-9
>high in frequency or if the unit could use some maintenance. The
>suggested drift of 1e-11 per month would add up to 1.5 e-9 over 13
>years, so it may well be within spec and need some C-field adjustment.
>Unfortunately, when it was mounted in its box, the C-field adjust hole
>was covered up. I'll need to power it down and do some disassembly and
>drilling to make that adjustment accessible.
>Suggestions? Comments?


drill an hole, turn the trimmer and zero it. It's a perfectly 
legitimate offset,
and since you see a straight line it's working well. Only it needs to 
be zeroed.

Do it after a few hours of warm up, then check it for a week and zero again.
It will stay in the usual +/- 1E-11 per day.

If it has the EFC option, may be that the external voltage was used to correct
the drift, so it may have had even a smaller drift over it's life.

Marco IK1ODO

More information about the time-nuts mailing list