Fig. 1 - HP 180D General purpose oscilloscope Fig. 2 - front panel - HP 1801A and HP 1821A Fig. 3 - Plug-in unit HP 1801A and HP 1821A inside Fig. 4 - Plug-in unit HP 1801A and HP 1821A inside HP 180D General Purpose Oscilloscope The HP 180D is a general purpose oscilloscope, fully transistoized with plug-in capabilities. This oscilloscope is designed to display complex high frequency waveforms and to measure alternating and direct-current voltages. It is rack instrument type with built-in till stand and bottom-mounted feet. It may be bench operated or rack mounted. The HP 180D has been designed to operate with a number of different plug-ins. The power supply is modular and may be disconnected and removed from the instrument for access to all components. The HP 180D used a post-accelerator aluminized CRT with an eight by ten division display area. The CRT accelerating potencial of 15 kV provides bright visual display. It simplifies the measurement of low duty cycle signals. At the rear panel it has a connection for input of an external signal for intensity modulation (Z-axis input). The HP 180D Oscilloscope requires time base and vertical or sampling plug-in units. For HP 180D was available about eleven Vertical Plugins and seven Time Base Plugins and two TDR. Horizontal amplifier - External input   Bandwidth: dc to 5 MHz dc coupled 5 Hz to 5 MHz ac coupled Deflection factor: 1 V/div, x1 0.2 V/div, x5 0.1 V/dix x10 accuracy ±5% Vernier provides continuos adjustment between ranges. Dynamic range: ±20V Maximum input: 600 Vdc (ac coupled input) Input RC: approx 1 MΩ shunted by approx. 30 pF