A bit off board topic but responding to changing pre set 122 frequencies.
I think before anyone starts inventing a different UK Band Plan for UK 122 Frequencies from the current frequencies already in use they should get some operating experience in to understand what might be required.
Its extremely unlikely more than a couple of frequencies are needed as communicating over any distance high gain antennas are needed.
This means with the sort of beamwidths involved, ~0.5 deg. its unlikely you will hear someone on an adjacent hill top a Km away unless beaming at each other. Power is uWs not even mWs.
Rifle scopes etc are needed for alignment such is the beamwidth of a decent antenna even for 5Km. Two dishes, one at each end will add something like around 90db to the link budget.
Take the dishes off and the loss to the link budget will be perhaps 50db. This means broader but still semi directional antennas will send significantly less power so again its unlikely to be a problem to anyone not in the next field.
First we need to get on and use what we have to get some more experience under our belts.
IF frequencies. Most operators will want to use a double ovened OCXO reference. These will almost certainly have EFC and its a simple matter to offset it slightly from 10 MHz to cope with any radio ceasing tuning below 144.
A multi turn adjustment pot will allow searching by moving the reference when necessary and returning to the bogey setting when offset is not needed. I would expect very few operators would not be able to tune below 144 with the number of FT790 and FT817 receivers around used for portable operation.
73s John G8ACE Utube UKG8ACE