Thanks Darrel,
In this part of the project (maybe the only part) I'm making the pulses, eight in a row for eight RC servo channels, of varying periods, rather than reading them. The TMR1 interrupt is just keeping the overall frame timing right.
Looking it now I think a tight loop reading the roll-over flag of the counter then doing the pulse train code would have worked just as well. I guess I thought that a real timer interrupt would minimise jitter in the total frame length.
Never mind, I'll carry on with the interrupt method now that I've started it.

I'd still like to see Alains code though.... Alain ?

Martin