Charles,
I emailed a reply to you, but it bounced. So here is what I said:
I can't answer your questions, but I think it would be a good idea for
you to join the RSGB Technical reflector and ask the
http://groups.yahoo.com/group/rsgbtech/
You don't have to be an RSGB member to join the reflector, and I know
that the people there are very helpful.
Good luck.
--
73
Ian, G3NRW