Tag says "Frequency Display Unit - General Electronics 14D2-S5" This looks to be a 1970's milsurp panadaptor. Fits in a standard rack slot 19x~6. 3"CRT. I've been told it uses "an oddball IF". Any idea what that would be? Any operating instructions out there? Nothing on-line so far. Cheers! Jim Falls K6FWT Eureka, CA