hi i wonder if anyone can help me out i have just picked a small cw/rtty filter unit type bp12 it seems in good condition but i did not rx any docs or info with this very small unit the company has ceased to exist and i have been unable to get any handbook schemetric diagram or info does anybody have any info please the unit runs on dc voltage between 7 to 14 volts that is all i know please any info would help thanks mike 73's