The Tektronix PS501 is a 0-20 V, 0.4 A + 5 V, 1 A power supply plug-in for the TM500 system. The 0-20 V 0.4 A output is floating, the fixed 5 V 1 A output is ground referenced.
The PS501 and PS501-2 have coarse/fine potentiometers for setting the variable output voltage.
The PS501-2 additionally features an analog meter to monitor voltage or current.
The PS501-1 has a 0-10/10-20 V switch and a 10-turn pot with mechanical voltage readout.
All versions have a 0-400 mA current limiting pot and an output switch.