The Tektronix 4701 is a multiplexer introduced in 1971 that allows several signals to be displayed on a single oscilloscope or captured with a recording instrument. The 4701 contains logic for round-robin switching between the inputs. The signal path bandwidth is DC to 1 MHz.
Each of the eight inputs to the Tek 4701 is differential. Each differential input signal goes into a discrete amplifier using a 151-1036-00 dual n-channel JFET. The output of the discrete amplifier is fed to another differential amplifier, this one using a CA3030 opamp. This second stage converts the differential signal to single-ended and provides a low output impedance. The low-impedance single-ended signal is fed to a diode switch. There is a summing junction where the outputs of the diode switches meet, thus forming the multiplexer. An output amplifier buffers the voltage on the summing junction, producing the low-impedance output for the rear panel connector.