Abstract :
Advertisement: The PAR Model PPMS-1 is a self-contained system consisting of the basic components required for making one part per million measurements of external resistance ratios or external DC voltages extending to 1000 volts. The system, with accuracy traceable to N.B.S., consists basically of a 10 volt DC source whose saturated standard cell reference is housed in a proportional temperature controlled oven (maintained within 0.001°C), a self-calibrating 7 decade Kelvin-Varley divider and a null indicator having a basic full scale sensitivity of ±1 microvolt. An output signal fully isolated from, but proportional to the deflection of the null meter is provided to drive strip-chart recorders and thereby function as a selfcontained monitor of the stability of other voltage supplies. In addition, this unit can serve as the controlling element in ultra-stable variable voltage or current supplies with the addition of power amplifiers which are available as accessory items. A unique method of self-calibrating the four most significant decades of the Kelvin-Varley divider without additional equipment as well as means of verifying oven temperature and standard cell voltage are provided. Price $4950.
