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3000 and 4000 RPM –0 to 100,000 hours
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Sensing from Magnetic Sensor, Battery
Charging Alternator or Ignition Signal
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High Visibility Analog Readout
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Air Core Movement
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Easy Calibration
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Through Dial Lighting
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Powered by 12 VDC Battery
Available Converter for 24 to 12 VDC
Description
The AT Series tachometers are rugged, transis-
torized 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
models are also equipped with hourmeter to
record the elapsed running time of an engine.
Models available for Alternator, Magnetic
Sensor or Ignition signal
These instruments are designed to function from
pulses generated by an alternator with 4, 8, 12,
14, or 16 poles on the rotor. The pulses can also
be obtained from the ring gear of an engine by
means of an electromagnetic sensor (magnetic
pickup). Murphy’s magnetic sensor driven mod-
els are designed to function with flywheels hav-
ing anywhere from 70 to 225 teeth.
Ignition signal model available for 4, 6 or 8
cylinder, spark-ignated engines.
All models are for negative ground, positive
ground or isolated electrical systems and are
protected against reverse polarity hookup.
All models are powered by 12 VDC and are
reverse polarity protected.
Series Models
ATS Series Magnetic Sensor Signal Tach
70 - 225 pulses
*
12 VDC, 2733 Hz to 13.62 kHz
@ 3000 RPM
ATHS Series Magnetic Sensor Signal
Tachometer/Hourmeter
70-225 pulses
*
12 VDC, 2733 Hz to 13.62 kHz @
3000 RPM
ATA Series
Alternator Signal Tachometer
3-27 pulses
*
12 VDC, 137 to 1330 Hz @ 3000 RPM
ATHA Series
Alternator Signal
Tachometer/Hourmeter
3-27 pulses
*
12 VDC, 137 to 1330 Hz @ 3000 RPM
or 193 to 1815 Hz @ 4000 RPM
ATHI Series
Ignition Signal
Tachometer/Hourmeter
4, 6 or 8 cylinder engines @ 4000 RPM
Applications
These tachometers are specially designed for use
on truck, marine, industrial, or stationary engines.
Specifications
Power Input: 12 VDC (11.5 to 16 V)
[0.84 to 1.44W].
Back Light: 3 to 4.7 W.
RPM Input Signal Voltage: 1.5 Vrms min. from a
magnetic pickup or alternator (minimum 3-pole).
Accuracy: Tachometer: ± 2% full scale.
Hourmeter: ± 0.01% hours, ± 1 count.
Temperature Range: -5 to 185°F (-20 to +85°C).
Dial: 270° sweep (white numerals over black)
Bezel: 304 Stainless Steel.
Scales: 0 - 3000 RPM or 0 - 4000 RPM
†
.
Case Material: Plastic.
Hourmeter Range: Measures elapsed time:
100,000 hours in 0.1 increments (tenths).
Shipping Weight: 0.89 lb. (403 g).
Shipping Dimensions: 5-1/2 x 5-1/2 x 5-1/2 in.
(140 x 140 x 140 mm).
AT and ATH Series
Bezel Styles
bright stainless
black stainless
bright SAE
black SAE
**
TAH-97026B
Revised 05-05
Catalog Section 20
(00-02-0260)
Tachometers and Tach/Hourmeters
TAH-97026B page 1 of 2
*
To determine pulses per engine revolution, work the
formulas on the back page and use the pulses per revolu-
tion number to determine if the tachometer can be used
for your application.
**
Products covered by this bulletin comply with EMC
Council directive 89/336/EEC regarding electromagnetic
compatibility except as noted.
†
Range available only for ATHA-40-12-A; ATHI-40-12-A