The Tektronix Type Q is a transducer and strain gauge preamp plug-in for 500-series scopes.
It can work with resistive, capacitive, or inductive transducers or strain gauges that are attached via an Amphenol 165-15 connector.
The plug-in contains a 25 kHz oscillator that is used to drive a Wheatstone bridge. This AC excitation / demodulation principle limits signal bandwidth to 6 kHz.
Type Q was introduced in 1960 and was the last all-tube plug-in. It was dropped after 1972.
Rotan plug-in prototype, likely led to Type Q