012-0259-00
The Tektronix 012-0259-00 Current Loop Adapter is an accessory for calibrators on 7000 series oscilloscopes having 1 mm jacks, such as the 7603 mainframe.
The Tektronix 012-0341-00 Current Loop Adapter is similar, but has a BNC connector instead of the 1 mm jacks.
Attached to the 4 V output jack, it provides 40 mA of current for calibrating clamp-on current probes like the P6021, A6302 and others.