To all... Here is ( yet another ) Doppler DF... http://www.silcom.com/~pelican2/PicoDopp/PICODOPP.htm This one is pretty slick, though... RS232 and IrDA outputs, and a Joe Moell wideband antenna design. ( = good sensitivity ) About a dozen are in service now, with good results reported from the users who provided feedback. TNX DE WB6EYV