Murphy AT-30 12/24 VDC Tachometer Part No. 20700245

The AT-30 tachometer is a rugged instrument with solid-state circuitry for indication of engine RPM. It is equipped with a ring nut for mounting into a standard 3-3/8 in. (86 mm) dash mounting hole.
A full 240˚ sweep of the pointer gives an accurate indication on a large easy-to-read scale, and the dial can be illuminated for night reading.
This AT Series tachometer indicates engine speed in revolutions per minute (RPM). Models equipped with an hourmeter (ATH Series) also record elapsed engine running time when the engine speed is greater than 100 RPM.
Calibration has also been improved and is now accomplished with a single push button on the back.

Specifications:

Power Input: 10-32 VDC (100mA max at 32 VDC, does not include backlight)
Backlight: Red LED Backlight Current: 75 mA Max. (@32 VDC)
Accuracy: Tachometer: +2% full scale
Hourmeter: +/- 0.02%
Operating Temperature Range: -40øF to 185øF (-40øC to 85øC)
Dial (Face Plate): 240 degree sweep; white text and graphics on black background
Bezel: 304 stainless steel Scale: 0-3000
RPM Case Material: Nylon, 12% glass filled, black
Lens: Tempered glass
Clamp: Screw-on ring, PBT, white
Max Panel Thickness: .50
Fits a standard 3-3/8 in. (86 mm) dash mounting hole
Hourmeter Range: 99999.9 hours in 0.1 increments. Begins counting when receiving an engine running input signal of at least 100 RPM.
IP Rating: IP66 Front, IP32 Back (vented case)
Input Voltage: 12VDC or 24VDC (10 to 32 VDC).
Not for use with Capacitive Discharge (CD) ignitions or magnetos.
Frequency Input Range: 2.5 Hz - 25 KHz
Minimum Signal Amplitude: 1.5 Vrms
Maximum Signal Amplitude: 140 Vrms
Mag Pickup: 50 to 300 flywheel teeth
Alternator: 3 to 52 pulses per rev
Ignition: 2 to 10 cylinders (4 cycle)
Operating Current: 100 mA Max. (@32 VDC) (does not include backlight)
Connections: 10-32 UNF studs (Battery +, Ground, Signal), 1/4 Spade (Backlight)
Electromagnetic Compatibility: 2004/108/EC