Hi Rolf, You are switching the ground for your RF circuit and antenna. Even if you added additional AC coupling to ground it still seems like a bad idea to me and something I would never do unless circumstances forced me, and then I'd test it both ways. Cheerful regards, Bob -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist