The ZX74 Series of Decade Resistance Boxes are very high accuracy and stable six-dial instruments. There are 4 versions in the series with a maximum resistance of 1,111,111ω. The ZX83 series adds another two Decade Boxes that extend the resistance range to 111,111,100ω.
The resistive elements are non-inductively wound on high quality formers using a resistance wire of specially selected alloy. Each resistive element is heat treated and undergoes a controlled ageing process to produce the very highest stability and also a low temperature coefficient.
Switches are of the highest quality with low pressure contacts for long life and reliability. Each decade switch is manufactured using a fully enclosed construction for maintenance free operation. These decade boxes are housed in attractive robust metal cases with a retractable carrying handle.
The very popular ZX74 model has a lowest decade with steps of 1mω. This is particularly useful for Resistance Thermometer Simulation and resistance bridge networks. All models have an extra terminal connected to the electrostatic screen which may be required in AC. bridge applications.