Many thanks for your reply and sorry for the delay Jan.
I'm quite pleased when we don't have freezing rain, but I need it to test things properly
. I am however certain of some things:
The condition only occurs when the link is error prone and marginal - the link will have been completely lost for some period and then have recovered;
I have thought that the radio RRC thinks it is being continuously keyed and therefore stops the keying. However, I realise that I don't actually know which RRC decides the keying has been going on too long;
There is definitely no continuous physical keying input to the control RRC;
The problem is cured by rebooting both the local and remote RRC - either one alone will not fix it - and no other changes are necessary for a fix.
My memory is that the control RRC is not showing that it is continuously keyed, but that is a year ago and my memory could be wrong. I will check when we next get some horrible weather.
73 Roger
VE3ZI