[time-nuts] Ultra Stable Rb

[martyn at ptsyst.com]

Hi Guys,

Just though you'd be interested in my prototype rubidium frequency standard
I made in the 1990's.

http://www.ptsyst.com/RFS10-FrequencyDrift.pdf

I have measured its frequency at random intervals for the past 18 years.

Its never been adjusted and is just free running.

It was turned off in 2005 and sent to a customer in Japan for a few weeks,
then returned and turned back on.

For the past 18 years its stayed within plus/minus 3 x 10E-11.

The overall linear drift is something like 1.85 x 10E-13 per month.

This is not an advert.  There's no way any of our production units are as
good as this one, well I assume so as I've never measured any for 18 years
continuous!

Its now over 25 years old, have hardly ever been turned off.  Any day I
expect it to fail, but it keeps on running!!

Regards

Martyn