In article ,
Tom Horne wrote:

We would like to be able to use 50, 144, 220, and 440 MHz
radios at any position and we would prefer not to have to resort to diplex
ers and separate antennas on the roof if it can be avoided.

Tom-

Phil and CRN have good suggestions that directly address your needs.

Another approach for common local frequencies, is to have a single base
station for each frequency, with a remote control at each position.
This allows the base station to be located (in a separate equipment
room?) closer to the antenna to minimize feed line loss. All it takes
is telephone wires to connect between the base stations and remotes.
Each remote could have a switch to select base stations.

Fred
K4DII