The Keithley Model 510 Megohmmeter utilizes a unique logarithmic circuit
to present six decades of resistance on a six-inch mirror-scale panel
meter. With so great a dynamic range, range switching is not necessary,
and the speed and ease of measurement are greatly increased.
Because of the logarithmic ocale, the usual high-end scale compression of
a conventional ohmmeter is eliminated. An accuracy within l$ of the scale
length is maintained at every point on the scale; this is equivalent to an
accuracy of about lO% of the resistance being measured. It is limited only
by the meter accuracy, and is about as good as conventional megohmmeter
circuits at mid-scale, but superior to conventional circuits at other than
mid-scale meter readings.
Test potentials of 5, 50 and 500 volts are furnished. They are useful in
measuring voltage coefficients, and offer freedom in selecting a safe
potential for all test samples.