[time-nuts] hm H Maser

[Bruce Griffiths]

Bob
As long as one stays away from CPT and merely uses the laser as a replacement for the traditional rubidium lamp plus filters it should be easy enough as one doesnt need to modulate the laser at 3.4 GHz.I was thinking something along the lines of the recent PhD thesis that gave all the detail required to duplicate their low noise rubidium standard that was quieter than am HP5065.One could easily substitute ones own ECDL (These can easily be constructed from commercially available parts) and improve somewhat on the performance (The oven design of most commercial ECDLs seems suboptimal).
Bruce 

    On Monday, 9 January 2017 10:23 AM, Bob Camp <kb8tq at n1k.org> wrote:
 

 Hi

The large diameter Rb cells are a bit harder to come by than the more generic telecom 
sized cells. I suspect you are correct and they are out there from somebody.. The real 
advantage you would have with an Rb is that the design you do is gigantic compared to
what everybody is doing today. Their constraints are not your constraints. 

Based on the laser driven Rb on my bench …. don’t bother with that part of it. It is indeed
doable. Doing it in a fashion that gives you a better standard …. not really easy at all.

Bob


> On Jan 8, 2017, at 3:55 PM, Bruce Griffiths <bruce.griffiths at xtra.co.nz> wrote:
> 
> The rubidium standard appears much more manageable given that the cavity dimensions are somewhat more compact and rubidium vapour cells are readily available. Substituting a laser for the lamp should also help in improving the reliability. However an ECDL laser locked to a rubidium line is required for a double resonance setup. Building ones own ECDL doesn't appear to be particularly daunting, however low noise drive electronics will be required. All the necessary optics are off the shelf items.
> One still has the issue of  the frequency pulling due to the presence of the vapour cell.
> Bruce
> On Sunday, January 08, 2017 10:22:54 AM you 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
> > 
> > > On Jan 8, 2017, at 6:01 AM, Bruce Griffiths <bruce.griffiths at xtra.co.nz>
> > > wrote:
> > > 
> > > You could try a cavity like the one
> > > in;http://tf.nist.gov/general/pdf/156.pdf
> > > 
> > > This avoids the requirement for a fused quartz storage bulb.
> > > Bruce
> > > 
> > >    On Sunday, 8 January 2017 11:33 PM, timeok <timeok at timeok.it> wrote:
> > > Hi,
> > > the thought of being able to work on building a H Maser has always
> > > accompanied me in recent years. I fully understand the many difficulties
> > > of this project and also the necessity of a work team. Maybe a Passive
> > > Maser would be easiest to implement, but I do not know in detail the
> > > processes of construction of the physical part of the interrogation.
> > > Honestly, I would love to spend My next ten years on a project like this,
> > > but... my curiosity is to know of there are other people with these
> > > mental disorders on earth.
> > > 
> > > If you want to answer me.
> > > Luciano
> > > www.timeok.it
> > > _______________________________________________