[time-nuts] hm H Maser

Ole Petter Rønningen opronningen at gmail.com
Tue Jan 10 10:35:43 EST 2017


... having said that, I for one think I'm with Bob on this one. The thing about masers are that they are big. At least active masers. And they require a substantial volume be kept at ultra high vacuum - which is not trivial, especially not in a homeshop. The cavity needs to be kept at a temperature stable to 0.001 degree C. With 4-5 magnetic shields. Add to this costly pumps to keep the vacuum this low even if you succeed at reaching that vacuum.. There's easily 1-2KUSD running cost per year just to keep the maser running.

Granted, I've never built a maser, but personally I think the problems that would need to solving (and lead to learning) would be much more on the vacuum-systems, shielding and temperature long before electronics becomes a major factor. And the chance of  actually get a result comparable to a commercial maser (or even just better than what you could realistically pick up from ebay for a few K) are pretty slim. And LOT of time and cash would be burned before you are even close to getting some sort of oscillation.

A rubidium does look like a more realistic project.. 

Dont get me wrong - it would be beyond cool if someone built a homemade maser. The first ones were built by regular people in regular labs, so sure it can be done.

Well, my $0.02 has been spent..
Ole

> Den 10. jan. 2017 kl. 15.15 skrev Ole Petter Ronningen <opronningen at gmail.com>:
> 
> Not sure how relevant that particular example is. PHM on Galileo was new science (at least the sapphire loaded cavity), and *very* different reliability engineering.
> 
> AHM's are nothing new, the science hace been done, the construction is known, down to exact drawings and circuit diagrams. There are numbers from 1982 that can possibly be used as a startingpoint for estimating an amateur project in https://library.nrao.edu/public/memos/vlba/main/VLBA_65.pdf
> 
> As a side note, I am also not convinced that sourcing the fused quartz teflon coated bulbs would be a show stopper for a limited number (<5) of masers, I for one have one on my shelf. It is quite possible that old bulbs for previous designs exists with the current manufacturers that they might be willing to part with.
> 
> They are also still manufactured, Vremya or one of the others might be willing to sell them - although I have no idea about the cost.
> 
> As another side note, on a trip to Switzerland I was allowed a glimpse of a couple of the PHM's for Galileo in person. Impressive. 
> 
> Ole
> 
>> On Tue, Jan 10, 2017 at 2:18 PM, ewkehren via time-nuts <time-nuts at febo.com> wrote:
>> Do we know what the PHM development for Galileo cost?
>> 
>> 
>> 
>> 
>> Sent from Samsung tabletBob Camp <kb8tq at n1k.org> wrote:Hi
>> 
>> > On Jan 10, 2017, at 2:45 AM, Dr. David Kirkby (Kirkby Microwave Ltd) <drkirkby at kirkbymicrowave.co.uk> wrote:
>> >
>> > Once 9 Jan 2017 12:59, "Bob Camp" <kb8tq at n1k.org> wrote:
>> >>
>> >> Hi
>> >>
>> >> Ok here are some rough numbers:
>> >>
>> >>> On Jan 9, 2017, at 4:35 AM, Dr. David Kirkby (Kirkby Microwave Ltd) <
>> > drkirkby at kirkbymicrowave.co.uk> wrote:
>> >
>> >>> It would be interesting to see your breakdown of the costs and man hours
>> >>> for an H2 maser. I suspect that others would find cheaper/faster
>> > solutions.
>> >>
>> >> $100M for the H2
>> >>
>> >> $25M for the Rb
>> >
>> > With all due respect,  and I apprectiate you have a good knowledge of this
>> > field, but that's not a breakdown of costs or man hours I wanted to see,
>> > but a cost which appears to be plucked from the air.
>> 
>> Hardly plucked from the air. The last Rb design that I was involved with was
>> roughly 5X that expensive.
>> 
>> >
>> > There's a BIG difference between a volunteer effort where
>> >
>> > * Salaries are not paid
>> > * Items of test equipment are likely to be borrowed or people provide
>> > access to them for no charge etc,
>> > * Academics are likely to provide consultancy for free, in return for being
>> > on papers published.
>> > * Software licenses could probably be obtained free,  or enough people get
>> > trials.
>> 
>> That’s where the 5:1 cost reduction comes from.
>> 
>> >
>> > compared to a commercial company building a maser where
>> >
>> > * Salaries are paid
>> > * All equipment is purchased new
>> > * Bench power supplies with 3.5 digit displays are sent out for calibration
>> > each year.
>> > *  No outside body will do anything except at a commercial rate.
>> > * Flights are booked for meetings which could be done over the Internet.
>> > * High end software licenses are huge.
>> >
>> >> $500M for the fountain.
>> >
>> > But on what basis do you arrive at that figure?
>> 
>> The numbers that the people who have done it come up with when you talk to them.
>> 
>> >
>> >> To get sponsorship for anything remotely close to those numbers, you
>> >> need to have some massively good credentials.
>> >>
>> >> Bob
>> >
>> > Yes agreed at $500M. But someone like Tom, who does have massively good
>> > credentials, could perhaps get $500,000, and perhaps that wisely spent
>> > could get a fountain built.  Without knowing how you arrive at $500M, it is
>> > not possible for anyone to look at ways of shaving that cost.
>> 
>> 
>> This is *not* a cheap field to be doing things in ….
>> 
>> Bob
>> 
>> >
>> > The Lovell Telescope at Jodrell Bank in the UK was built on a shoestring
>> > budget. It was at the time the world's  largest steerable radio telephone.
>> > Half a century later only 2 larger ones have been built.
>> >
>> > Maybe I am too nieve.
>> >
>> > Dave.
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>> 
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