Hi > On Jan 10, 2017, at 5:26 PM, Bob Stewart <[email protected]> wrote: > > 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)?
Pretty much none. You *can* design one with a crummy OCXO, but the question becomes - why would you do that? Putting a $10,000 OCXO into a $150K device is not that big a deal. If you put the same OCXO into a Cs standard, it would run a bit better out to the cross over point (a few 100 seconds or so). Indeed *some* Cs standards have such OCXO’s in them and that’s what they do. Bob > Bob > > From: Dr. David Kirkby (Kirkby Microwave Ltd) > <[email protected]> > To: Discussion of precise time and frequency measurement <[email protected]> > 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 <[email protected]> > wrote: > >> ... 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. > > Dave > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > > > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
