> While I'll agree that more isolation, then what is needed to
> insure no desense is a waste; if this gentleman is suggesting
> that isolation in reserve is a waste, I strongly disagree.
> Why? Operating conditions can change - snow and especially
> ice on the repeater antenna can detune the system and
> isolation in reserve will allow the repeater to operate
> without desense until the reserve is used up.
>
> Kevin Custer
Aso, if you're going to err on the side of being conservative in your
isolation requirements, such as contemplating a 6 cavity duplexer instead of
4 if you think you're on the hairy edge, consider using bandpass cavities
instead of pass-reject for that added cavity on each side. The extra
out-of-band rejection that a true bandpass cavity will give you will afford
more protection to/from other co-located or nearby stations, including those
that might show up months or years down the road...
Spend the extra money on the added isolation if there's any doubt. A few
tenths of a dB of added insertion loss from an extra cavity is never going
to be noticed by users, but desense most certainly will be.
--- Jeff
