Aim-TTi BS407 Micro Ohm Meter

The BS407 is an instrument which is fully optimised for the task of accurate measurement of low resistances with a best resolution of 1µOhm.
Most multimeters offer a best resolution which is at least one thousand poorer than this. A very high resolution multimeter may attempt to resolve fairly low resistances, but it does so by resolving extremely low voltages (typically one Nano-volt per micro-ohm), making it subject to severe errors from thermal EMF effects and noise.

In contrast, the BS407 generates sufficient test voltage across the unknown resistance to combat noise and reduce thermal EMF effects to manageable levels. Current reversal can then be used to eliminate any remaining thermal offset.

The BS407 uses a four terminal measurement system via high quality Kelvin Clip leads (supplied). For speed and convenience front panel switches are provided for current diversion (allowing in-situ zero adjustment) and current reversal (for identifying thermal EMF errors). An LED indicator warns of open circuit leads thus preventing spurious results from being recorded.

• High basic accuracy of 0.1%
• Wide range of 1µ Ohm to 20kΩ
• Current reversal switch for detecting thermal EMF effects
• Current diversion switch for easy zeroing
• Four terminal measurement using Kelvin clip leads
• Battery operation with built-in charger
• 20mV clamp for dry circuit testing
• Manufacturers part no. Thurlby Thandar BS407