The C1-118 (S1-118 / С1-118) oscilloscope was produced in the USSR in 1982 - 1988.
It is a small portable 2-channel analog oscilloscope with a 10 MHz bandwidth.
There was also an enhanced version C1-118A (S1-118A / С1-118А) with a 20 MHz bandwidth produced in 1988 - 1989.
The C1-118 and C1-118A oscilloscopes weigh only 3.8 kg (without accessories). The width is 21cm, height 12cm, depth 33cm.
The input impedance of both channels is 1 Megaohm, 20 pF. Vertical sensitivity from 5mV to 10V per division, +/- 5% accuracy.
The time base horizontally is 50ns - 50ms / div in C1-118 and 20ns - 50ms / div in C1-118A. It has +/- 5% accuracy.
The CRT tube is soviet oscillographic 11LO9I (11ЛО9И) with electrostatic deflection, a useful 8 x 6 cm screen area, 6.3V 80-100mA heater and 8kV anode voltage.
The scope has brightness and beam focus knobs, horizontal trace alignment, vertical alignment of each trace.
Synchronization level setting, rising / falling edge trigger switch, external / internal sync switch, TV / NORM switch, and YI or YII channel sync switch.
Each channel can be switched off to use only the other. Input for external (EXT) sync and grounding socket.
Adjustments of Y amplifiers and the timebase are accessible from the outside (from top and from sides).
It has power switch and indicator lamp. You can choose between two multiplex modes of the channels when using two traces (chopper / alternate).
It is powered from 220V 50Hz-60Hz mains, it says 28VA consumption, I measured 23W.
My piece comes from 1988, originally used as a school aid, fully functional. The protective cover for the front panel is missing.
C1-118 schematic part 1 - CRT, high voltage inverter, deflection plate drivers, brightness, focus
(slightly different version with resistor and capacitor values)
C1-118 schematic part 2 - time base and triggering
(different version, probably C1-118A)
C1-118 schematic part 3 - vertical amplifiers (Y), trace switching, mains power supply
(slightly different version, poor image quality, but with resistor and capacitor values)
