Tesla BM370 vacuum tube oscilloscope

The description of this beautiful vintage scope is under construction ...
You can take a look at its schematic and photos ;)

Tesla BM370 vacuum tube oscilloscope schematic (click to enlarge).

Tesla BM370 scope

Tesla BM-370

Tesla BM370 oscilloscope - back panel.

Tesla BM370 oscilloscope with C1-118.

BM 370 has a horizontal input, so we can display Lissajous curves. Here I use sawtooth waveform instead of a sine wave.

Tesla BM370 without cover.

Glowing vacuum tubes 6Z31, 2x EF80 and EF183 in Tesla BM370 scope.

Regenerating the electrolytic capacitors by very slowly charging them via a high resistance resistor.

Tesla BM370 oscilloscope

BM370

Tesla BM370 - inside.

BM370 disassembled

BM370

With a very dodgy makeshift mains cable!

BM370 analog oscilloscope teardown

Tesla BM370 - after removing the 7QR20 electrostatic CRT tube.

7QR20 oscilloscope CRT made by Tesla

Some more Lissajous curves in a sawtooth version.

Mains voltage switch set to an unlabeled position for 230V. By rotating it from the 220V position two pins clockwise, we actually arrange the primary windings for 230V (110 + 110 + 10), which is now used in Europe. Comrades were just prepared for everything :).

Spare 7QR20 CRT tube for the BM370 oscilloscope.

Original datasheet of the 7QR20 made in 1961.

Added: 7. 3. 2018
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