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Remote/Internal
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Internal Optics
Lens
Figure 1 HHT21A-R
with Optional Remote Sensor (HHT20-ROS)
CALIBRATION AND SELF-TEST
The HHT21A SERIES is a crystal controlled digital instrument that requires
no calibration. However, the accuracy of the instrument can be checked at
any time by aiming it at an old style fluorescent light and observing 7200 ±2
RPM. In countries with 50 Hz. power line frequency, the display will read
6000 ±2 RPM.
NOTE:
The Tachometer will not correctly read on energy-efficient
fluorescent lights.
BATTERIES
The HHT21A SERIES operates from four 'AA' size batteries which are
located under the hinged top of the instrument. To access these batteries,
grip the tapered cover at the optical lens end of the instrument and pull up.
The cover is hinged at the display end of the instrument and pivots fully out
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SPECIFICATIONS
This product is designed for indoor or outdoor use under the following
conditions (per IEC1010-1):
Speed Range:
Accuracy:
Recharger Jack
Resolution:
Display:
Display Update:
On-Target Indication: Target (Bullseye) on lower left of display
Operating Distance: Range:
Power-On Switch:
Optical System:
Time Base:
Power Source:
Recharger Input:
Temperature:
Humidity:
5 RPM to 100,000 RPM
± 1 RPM or .01% of reading
1 RPM
6-digit 0.45" high liquid crystal
Twice per second
of reflective tape
Angle:
edge of reflective tape
Pistol grip trigger - may be locked on with latching
push-button for longer duration measurements
Auto hold of last measurement for 90 seconds
Visible laser light source
WARNING:
AVOID EXPOSURE
Do not view the laser beam directly as it
LASER RADIATION IS EMITTED
FROM THIS APERTURE
could be hazardous to the eyes. Do not
point the laser beam into another person's
LASER RADIATION
AVOID DIRECT EYE EXPOSURE
eyes. Do not view the laser beam with
PEAK POWER
3mw
WAVELENGTH
650nm
telescopic devices.
CLASS IIIA LASER PRODUCT
Crystal controlled
4 "AA" batteries; Recharger socket provided for
optional rechargeable batteries
Max input 7.8 Vdc @ 50mA
41 °F [5 °C] to 104 °F [40 °C]
Maximum relative humidity 80% for temperature
up to 88 °F [31 °C] decreasing linearly to 50%
relative humidity at 104 °F [40 °C]
Up to 10 feet [3.1 m] from leading edge
Up to 45° from perpendicular to leading
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