Thanks to a loan from Perry W8AU, I've scanned the AN/URR-74(V)2 manual (this receiver is a Watkins-Johnson 8718A variant) http://www.navy-radio.com/manuals/urr74-8202.pdf n.b. The WJ-8718 manual is here http://www.criticaltowers.com/General%20Web%20Pages/Ham%20Stuff%20Page.htm Nick England K4NYW www.navy-radio.com