I am putting a VHF/UHF antenna in my attic and have run coax into two
different rooms in the house. I would like to be able to access the
antenna, on both bands, from both rooms in the house (not at the same time,
however). Is there a "remote" way I can do this, meaning without running
any more wires? I have been searching for an rf triggered relay that would
ground the second coax when a signal came down the first, but I can't find
anything like that. A duplexer won't work because I want to be able to
access both bands from both rooms. Certainly there is someone else in this
hobby who has done this, but I can't find anything on the Internet about it!

ANY suggestions would be welcome.

73,
Brett
KG4KLR

How about this untried idea.

A latching relay.. switched by a battery in the loft.
When you PTT up coax 1 a transistor is biassed to pull
the relay across to that coax and disconnecting the other
coax. I larg-ish electrolytic capacitor and resistor in
parallel as the relay sink, so the relay current drops off
to almost nil once it's changed. This would reduce overall
current drawn from the battery.

I wonder if something like that would work well?

Rv!

How about this untried idea.

A latching relay.. switched by a battery in the loft.
When you PTT up coax 1 a transistor is biassed to pull
the relay across to that coax and disconnecting the other
coax. I larg-ish electrolytic capacitor and resistor in
parallel as the relay sink, so the relay current drops off
to almost nil once it's changed. This would reduce overall
current drawn from the battery.

I wonder if something like that would work well?

Rv!