[time-nuts] hm H Maser

Dr. David Kirkby (Kirkby Microwave Ltd) drkirkby at kirkbymicrowave.co.uk
Sun Jan 8 11:21:28 EST 2017

On 8 January 2017 at 15:22, Bob Camp <kb8tq at n1k.org> wrote:

> Hi
> I guess the question then would be:
> Is a H Maser that runs 6.6 x 10^-12 at 1 second worth the trouble?
> With 100 KHz / C temperature coefficients running around, getting
> good stability in a real world setting at 1 day will be “interesting”.
> Just for reference:  The MH-2010 data sheet shows 1.5x10^-13 at
> 1 second for the “cheap” version and 8x10^-14 at one second for
> the low noise version.  Data showing the 5065 Rb at 1x10^-12 at
> 1 second is running around on various web sites.
> The NIST paper suggests that they made several prototypes before
> they got one good one working. That’s a lot of “fun and games” with
> ceramic machine lathes and Rb magnetometers…..
> The punch line being - would the same effort / cost / many years of time
> be more
> fruitful (ADEV wise) doing a large package Rb (like a 5065) ?  Based on
> the number of people making them in volume over the years, Rb’s appear to
> be the easier item to debug, design, and build.
> Bob

If you build a H2 maser, you would learn a lot more than building a bunch
of rubidiums. That sounds a good enough reason to me.

I've been contemplating buying one of the older HP 5061A or 5061B cesium
frequency standards from eBay. Almost all are sold as "for spares or
repair", and are probably not going to be economically viable to get
working due to the fact the tubes are probably useless. But I'd sure learn
a lot from playing around inside one of the older ones.


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