Produced from (?) to (?)
Technical manual TM11-6625-219-12, Operator's and organizational maintenance manual, Oscilloscope AN/USM-81. please add
The Hickok AN/USM-81 is a scope that takes
letter-series and 1-series plug-ins. It is an unauthorized clone of a
Tektronix 545A made for a defense contract by Hickok.
See also Jetronic AN/USM-81.