I understand how to do this, but can't find some info. What is the voltage/division for vertical and horizontal deflection of the scope. Find some info for 50mv/div, but not sure for this (after some reading of the calibration procedure for 067-0587-02 — Calibration Fixture I'm sure now - it is 50mv/div).
I think the easiest place to find it is in the standardizer service manuals and as I recall, it is 25mV/div per side or 50mV/div differential. (1)
I can try to make this extender - have some mainframe and plugins for spares and think that can be use connectors from it and to make a pcb to put all together with bnc connectors inside the extender.
I just left the cover off of the mainframe and off of the 7A16A vertical plug-in so my multimeter leads could reach the test points that I added.
DC volts on my multimeter allowed zeroing the output from the vertical plug-in to do the zero calibration of the mainframe and AC volts allowed adjusting the function generator and plug-in to produce exactly 1 div, 2 div, ect. peak-to-peak low frequency square waves for vertical calibration. An average responding AC meter reads 1/2 the peak-to-peak value 11% high and an RMS responding AC meter reads 1/2 the peak-to-peak value.
Then I moved the plug-in to a horizontal slot to do the same for the mainframe's horizontal circuits.
The transient response calibration needs a standardizer or the extender with the signal splitters to drive another faster oscilloscope.
(1) Confusingly, Tektronix sometimes calls this push-pull but that is fair since people now confuse differential with difference.