Tektronix DC 503A 125MHz Universal Counter Timer TM 500 Plug-In Test Module Unit

Tektronix DC509 Universal Counter Timer For Tektronix TM500 System Power

Tektronix DC 504A 100MHz Counter Timer DC504A TM 500 TM500 Plug-In Test Module

Tektronix DC509 Universal Counter Timer For Tektronix TM500 System Power

Tektronix DC504 Counter Timer Module #1

Tektronix DC 5010 Programmable Universal Counter Timer

VINTAGE Tektronix DC 505A Universal Counter Timer (PARTS UNTESTED)