An HP115AR Digital Clock, running against WWV. The vertical input on the HP122AR scope is connected to the headphone output of a Hammarlund SP-600 receiver, tuned to WWV at 2.5 MC (not shown). The trigger input for the scope comes from the HP115 1-second "Tick" output. The time base for the HP115 is the 100 KC output of an HP5245L counter (not shown).
