Fluke 709 calibrators fluke fluke 709 the fluke 709 calibrator is a 20ma loop device that can both source and measure current for ma loop systems 0 to 20ma and 4 to 20ma featuring best in class accuracy at 001 reading a resolution of 1 956a on ma ranges and 1 mv on voltages ranges this is a highly accurate and sensitive device it is also designed for the busy technician in the field with its compact rugged design and an intuitive user interface for fast setup supplied with a nist