Howell Instruments H1900

Signal Input

• One low-level DC input used to measure the output of the engine thermocouple harness. ANSI Type K thermocouple, range 0 to 1200 °C.
• Two frequency inputs usually assigned to monitor engine speed. Inputs from 5 Hz to 20 KHz, 500 mV to 50 Vrms, range 5.0 to 120 %RPM.
• Two discrete +28 VDC or 28V return inputs that can be used to monitor switch closures from weight-onwheels or bleed air switches.
• One analog 0 to 5 VDC, usually used to measure a signal from an amplified pressure transducer, for torque, EPR or PAMB.
• RS-232 input used for data uploading.

Signal Output

• One discrete +28 VDC or 28V return ouput that can be used to operate a caution panel or other warning device (limitation of 350 mA).
• RS-232 output used for data downloading.

Optional Input/Output

While many options are available, the most common are listed below:

• ARINC 429
• MIL-STD-1553B
• One resistance input (RTD) for measuring outside air temperature sensors.
• One synchro transmitter input for measuring engine pressure ratio (EPR) or inlet guide vane (IGV) type devices.
• One analog 0 to 5 VDC output.

Data Retrieval

• Two remote-mounted switches allow the operator to step through real-time secondary displays and interrogate or reset stored engine exceedance, usage or performance data. Password protection is available.

• Download data via the RS-232 output and optional download cable. This option will allow customer specific data to be transferred from the indicator to a PC or Laptop computer in a standard ASCII format. Customer-specified formats available at additional cost.

Special Features

• Re-programmable through the connector via software and RS-232.
• Calibration on condition, without opening the indicator.

Display

• A precision micro-stepper motor drives the analog pointer.
• The digital display features four, seven-segment LED characters with four decimal points. (NVG compatible per MIL-L-85762A). Brightness automatically controlled via an integral photoelectric cell.
• Accuracies for the digital display, from –40 °C to +71 °C ambient, ±3 °C / ±0.2 %RPM.

Warning Lamp (Optional)

• The H1900 Series employs an integral warning lamp, which can be supplied in red, yellow, orange or NVG blue/green or red. Activation point is set to customer specifications.

Ball Flag Indicator

• Electro-magnetic, latching, ball indicator, password resettable. Normally black, this indicator turns white to indicate an exceedance or maintenance action.

Internal Lighting (Optional)

• Internal lighting can be provided to operate from 5V AC/DC or 28 VDC system. Brightness controlled by the lighting rheostat in the aircraft. Available color options are white, red, blue/white or NVG.

Connector Interface

• MS3476W16-26S or PT06SE-16-26S (MIL-C-26482 Series I or II). Adapter harnesses are available to connect to existing aircraft harness, avoiding aircraft wiring change.

Certification

• TSO certification provided depending on application.

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