Keithley Model 1201 cathode follower probe

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An internet friend was restoring an HP 410B and dropped and broke the bezel :-(. We arranged to swap a replacement bezel from one of my HP 400H's for his Heathkit Tunnel Dipper. When I received the package with the dipper, I was delighted to find that he had included a surprise:

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 a Keithley Model 1201 cathode follower probe.

The internet doesn't seem to know anything about a Keithley Model 1201. I suspect it is the primordial hollow-state ancestor of the modern FET oscilloscope probe. 

I have yet to open it up. The probe body is nicely finished aluminum. The tail of the probe unscrews, though I haven't figured out how to detach the cable. It looks like the front will come off if I remove a couple of phillips head screws.

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It has an input impedance of 10 Megohms ...

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... shunted by 15 pF. The frequency response is 10 cps to 50 Mc. The accuracy spec for the 1 mV to 30 mV ranges is ±2% for 20 cps to 20 Mc, and ±3% for 15 cps to 50 Mc. For the 100 mV to 300 mV ranges the spec is ±2% for 20 cps to 10 Mc, ±3% for 15 cps to 20 Mc, and ±3 dB for 10 cps to 50 Mc.

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The probe has a UHF connector, presumably for the signal, ...

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... and what I think is a five-pin Cannon connector, presumably for power.

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I at first thought the probe went with some kind of RF millivoltmeter, but now I think the only missing piece is the power supply, and that the probe UHF connector was intended to mate with a Tek vacuum tube scope.

Does anyone have access to an old Keithley catalog?

© Steve Byan 2011-2016