Thanks for the informed replies people.
I know the basic rules give some set numbers of ranges but obviously there is going to be more to it as you have shown. I will take more account of terrain (and weather maybe too?) especially urban or players using hills to aid range/reception int he future.
Battery life will by an issue also, if rechargables are not available. Sounds like a VHF backpack radio with a good antennae is a must for a T2K party/group.
Another question - if anyone is bored
- my players also try to 'listen in' to other units who thay may know are operating in the area. I know the rules have a mention of built in encryption radios too but guess these are not foolproof (do they counteract each other?). My basic way of dealing with this is to have a hidden roll/chance of the enemy radio being in use at the time and of how useful the info may be and make the player roll a difficult electronics and relevant language skill. Any other ideas/input welcome.