Around the time the HP-8407 VNA was introduced they presented this active probe. But it was also usable for spectrum analysers and scopes.
The PSU was a supprise, I had not expected a 40W PSU just to feed 4 probes. A lot of HP analysers can feed this probe so the PSU is not always needed.
The box was missing the foam so I replaced that.
Some pages from the operation note.
