The ATH Series tachometers are rugged, transistorized instruments with solid-state circuitry for indication of engine RPM. They are equipped with a bracket for mounting into a standard 3-3/8 in. (86 mm) dash mounting hole. A full 270° sweep of the pointer gives an accurate indication on a large easy–to–read scale, and the dial can be illuminated for night reading.
The ATH Series are also equipped with hourmeter to record the elapsed running time of an engine. Available for alternator or magnetic signal pickup. These instruments are designed to function from pulses generated by an alternator with 4, 8, 12, 14 or 16 poles on the rotor (3 - 40 PPR). The pulses can also be obtained from the ring gear of an engine by means of an electromagnetic sensor (magnetic pickup). The Murphy magnetic sensor driven models are designed to function with flywheels having anywhere from 50 to 304 teeth. For negative ground, positive ground or isolated electrical systems and are protected against reverse polarity hookup. Powered by a 11-28 VDC battery and are reverse polarity protected. These tachometers are specially designed for use on truck, marine, industrial or stationary engines.