Spot the test equipment (Solved: HP214B pulse generator)

[capt bullshot]

Not so hidden at all, find the instrument that uses at least one vacuum tube (not the obvious ones)

[daqq]

Aside from the scopes with CRTs, maybe an electrometer? I think that some older types used a tube front end for extra high impedance.

[capt bullshot]

Aside from the scopes with CRTs, maybe an electrometer? I think that some older types used a tube front end for extra high impedance.

No, the scopes are the obvious ones, so they're not the answer. I don't have an electrometer, there's one of the instruments that incorporates at least one tube - I guess one can only tell it if one knows and recognizes the instrument

There's a higher resolution picture:


But you won't be able to read the instruments numbers, googleing them all would be too easy ...

[grumpydoc]

That HP 214B (with option 001) has valves in the output stage.

[capt bullshot]

That HP 214B (with option 001) has valves in the output stage.

Correct. It's two valves (actually a MOSFET / valve cascode configuration) in parallel to provide a 100V / 2A pulse output into a 50 Ohms load.
See the manual and some pictures inside: http://wunderkis.de/HP214B/

An interesting detail is on P1130391: The coax balun used for output polarity reversal. The output stage itself can only produce negative pulses, so for positive pulses, one of the relays connects the either the shield or the core of the coax to output GND. The output stage is built fully floating with either its positive supply rail connected to GND (the tubes / valves run on negative voltage) or the valves anode connected to GND (for positive pulses), the balun taking away the high frequency stuff away from the now pulsing power supply rails. Quite interesting concept.