TTi (Thurlby Thandar Instruments) has improved the accuracy of its BS407 micro-ohmmeter.

It can now resolve resistance down to 1µΩ, and has ranges with full scales from 2mΩ up to 20kΩ with a basic accuracy of 0.1%.

It uses a 4-terminal measurement system through Kelvin contact clips, with a maximum excitation current of 250mA.

Measurement current can be reversed to identify errors from thermal EMF.

A front-panel operated ‘clamp’ switch limits the maximum voltage across the unknown resistance to 20mV. "This is a requirement for the measurement of switch contact resistances to international standards," said TTi.

Another switch allows current diversion for in-situ zero adjustments.

The instrument is 220x82x230mm, weighs 1.3kg, and runs from internal NiMH cells.

For more info, see http://www.tti-test.com