Just goes to show how confused I can get!
Just tried the charger again and got an open circuit.
Now I've found out that it's nothing to do with the radio, but the intermediate plug between the charger and the Tx, all it needed was not to be fully plugged in, and I mean by fully that means it almost needs to be held together.
No idea why, as I have just checked the plug and it's all OK, but I changed it anyway, and the new one works fine.
So the wire has come out of the radio, and it still works.
Thanks for all your help, and at least I found out the problem, even though I still do not know what is wrong with the plug...
Steve