[time-nuts] Question for the cesium nuts.

[Tom Van Baak]

> > What do "active" and "passive" mean wrt masers?
> >
> > From the above data sheets, active means bigger and better.  (and probably
> > more expensive)
> >
> Hal
>
> Active  masers oscillate.
> Passive masers don't.
>
> Bruce

Another way to think about it:
  active masers oscillate;
  passive masers resonate.

Note the rubidium vapor and cesium beam atomic frequency
standards that many of us use are also of the passive type;
i.e., they lock a quartz LO by rapid probing of the resonance
frequency.

/tvb