[time-nuts] EFOS Maser turns 34!

John Miles john at miles.io
Sat Jan 7 17:47:41 EST 2017

> -----Original Message-----
> From: time-nuts [mailto:time-nuts-bounces at febo.com] On Behalf Of John
> Ponsonby
> ... It turns out that the resonant frequency of the cavity is much more
> critically dependent on its diameter than on its length. So it would be best
> to be able to mount the bulb in the cavity and to measure the resonant
> frequency with the cavity still in the lathe... 

This reminds me of an anecdote about the construction of the first NH3 maser in Charles Townes's book ("How the Laser Happened.")   They were having trouble with the irregularities in the cavity associated with the entrance and exit apertures for the ammonia gas.  They found it was better to get rid of the gas ports altogether and open the cavity completely at the ends, essentially replacing it with a long pipe relative to the resonant frequency at K band.  

Is that an option at 1420 MHz?  Or would the cavity pipe and storage cylinder have to be so long that it would be even more expensive to build (and to shield)?

-- john, KE5FX
Miles Design LLC

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