> -----Original Message-----
> From: time-nuts [mailto:[email protected]] 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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