A lot of us amateur microwavers retune circulators with external magnets. With
a handful of otherwise useless circulators, one could tear one apart, recover
the magnets, and apply them to the outside of the case of the unit to be tuned.
A network analyzer helps, so you can watch what's happening in both directions,
but that's not a requirement. You can tune them up or down quite a bit,
depending on the orientation of the external magnets. Once you find a
combination that works, the external magnets get glued to the circulator case
with epoxy.
Mel - WA6JBD
> Don't get your hopes too high, because most dual isolators
> can only be tuned
> 3% or so away from the frequency they were manufactured to
> operate at.
