[time-nuts] hm H Maser

Bob Stewart bob at evoria.net
Tue Jan 10 17:26:21 EST 2017

This may be a dumb question, but how much of an H Maser's advantage over a Cs Standard, for us mere mortal time-nuts, is down to the output oscillator it uses, rather than the reference source (H MASER or Cs beam)?

      From: Dr. David Kirkby (Kirkby Microwave Ltd) <drkirkby at kirkbymicrowave.co.uk>
 To: Discussion of precise time and frequency measurement <time-nuts at febo.com> 
 Sent: Tuesday, January 10, 2017 4:12 PM
 Subject: Re: [time-nuts] hm H Maser
On 10 January 2017 at 15:35, Ole Petter Rønningen <opronningen at gmail.com>

> ... 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.

Looking at the Microsemi MHM 2010 Active Hydogen Maser data sheet, the
maser has a peak power of 150 W and an operating power of 75 W.  Based on a
power consumption of 75 W, that is 657 kW hr / year of energy. I pay around
£0.20 (GBP) per kW hr for electricity, so that's £131 (GBP) annually. I
believe electricity is cheaper in the USA than here in the UK, but
converting £131 (GBP) to USD, that's around $161/year in electricity. So
running costs don't seem to be an issue.

But I must admit, the thought of spending a lot of time/money to build
something I could have bought for a lot less with higher performance is not
that attractive, although of course there would be a satisfaction from
building it yourself.

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