John,
you wil have to programme the PX-777 to the UK PMR freqs, this can be done by:
1) Holding down the black button on the side under the PTT button and the menu button as you turn the radio on. this puts the radio into program mode (it should display "Self"
2) press enter to display CH-001, press enter again to display the transmit frequency and enter 446.006 (notice that when you type it in a small 25 to complete the freq)
3)press enter again to display the CT code option, press the VFO/MR button to turn this off
4) press enter again to display the recieve frequency and enter 446.006 again.
5)press enter again to display the CT code option, press the VFO/MR button to turn this off
6) again for DT code press the VFO/MR button to turn this off
7) press enter to skip ADD
8) this is the power setting make sure it is set to L (low power to comply with PMR regs) by turning the knob on top of the radio next to the volume control.
9) press enter, this is channel width, make sure this is set to Narrow by the same method as step 8.
10) press enter and enter a name if you whish.
11) thats channel 1 set up.
now all you need to do is setup the other channles to the following frequencies by repeating steps 2)-11):-
446.03125 MHz
446.05625 MHz
446.08125 MHz
446.01875 MHz
446.04375 MHz
446.06875 MHz
446.09375 MHz
once done turn the radio off, and this time turn on by whilst holding down the enter key to turn the radio into "channel" mode now using the selector knob on top of the radio you can select between the different channels you have set up. Hopefully the channel numbers will correspond with your other PMR radios!
I have had my PX-777's for a week and they work really well, got them installed on the bikes at the weekend and perform very clearly and great range on low power.
any questions just ask!
Regards
Si