Smiths “Desynn” Portable Test Set. A specialist electrical test instrument designed for checking and calibrating Desynn (selsyn-type) remote indicating systems, commonly used in aviation and marine applications for tank level and position indication. The set allows testing of transmitters and indicators by simulating degrees of movement, with dual analogue dials marked in degrees and tank units, selector terminals, and wiring diagrams mounted inside the lid. Housed in a fitted wooden case with leads and connection sockets. Mid-20th century, c.1940s–1960s.
