HP 427A Voltmeter
The HP 427A Voltmeter is really a multimeter with the
ability to measure AC, DC+, DC- Volts and Ohms. It has a mirrored analog meter.
The black common 5-way binding post is isolated from the instrument chassis.
The AC measurements are average responding not true RMS.
Specifications:
AC Voltage Range 10 mV - 300 V
DC Voltage Range 100 mV - 1000 V
Frequency Range 10 Hz - 1 MHz
Interface 10 Mohm
Before the handheld DMM this was the general purpose lab
instrument used for common electrical measurements. It can be powered
from an AC line using the standard IEC power cord (110 or 220) or from an
internal 22.5 Volt Battery. There is a carrying handle on the top so it
can be used in the field like the DMM is used now. Maybe it could be called
an AMM "Analog Multi Meter".
This is a solid state meter that measures AC, DC+, DC- Volts and Ohms.
It has a mirrored analog meter. It's 1/3 Rack wide & will mount in 4
Units of height. The black common 5-way binding post is isolated from the
instrument chassis. The AC measurements are average responding not true
RMS.
The reason for the DC+ and DC- functions is because this meter reads up to
1,000 Volts on the DC range but may have a lower spec for the isolation between
the black common 5-way binding post and earth ground. Some power
supplies, like ones used for small Cathode Ray Tubes (CRT) have the positive
terminal connected to the chassis and the negative terminal is floated.
The 427A could measure these voltages either direction.
115/230Volts
1Phases
50~1000Hzs
