Many thanks to Charles, John, Paul, Guy and Nigel for their replies.
I have used a SB 220 for about10 years, with an Icom 751 first, then with a
K3. I got a Slow Key from Harbach, all worked normally, but I didn't notice
the key line was negative !
Otherwise I would have told my friend ( Gerard, F6CVM) not to connect
Anyway he ordered a Sofkey from Harbach and that'lldo the trick.
I saved your replies, gentlemen, and I'll read them more carefully when the
grand children have gone home, I shan't be so busy !
Thanks again and take care
Jacques de F9OJ