I’m aware of quite a few people who use the 1000HX for packet radio –
as the 1000EX is a very similar computer, the differences should be small.
Unfortunately, I don’t have their names/addresses handy :-/
You can purchase a serial board for the EX from:
DCS Industries or
as well as from your local Radio Shack.
I believe its approximately the same price for all of them.
I will e-mail the Tandy 1000 FAQ and you can find the addresses for
DCS Industries and PC Enterprises in it.