TM106601_(7/01) 2-
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convenient location for ease of operation and accessibility for inspection and maintenance. The area
should be free from excessive vibration, heat and electronic noise generating sources. If the system is
to be deployed in hot climate areas, additional air circulation/cooling around the RT1601 is
recommended. In addition, since all weather radar receiver-transmitter units are high power pulse
generating devices, they are potential sources of RFI. Consider this factor when selecting a location
for the RT unit. The cable should not be bundled with ADF loop lines. Other restrictions on unit
locations are those imposed by transmission line and waveguide length limits. It is recommended
that total waveguide length should be held to a maximum of 10 feet including bends.
Note
+
When the transmitter is keyed, a magnetic field
occurs, created by the heavy dc current drawn. A
magnetic shield P/N 4004660-0501 is available
when the R-T unit interferes with the magnetic
compass. The indicator contains a magnetic
shield that encloses the unit, eliminating this type
interference.
2.4.3 Primary Power Requirements
The RDR-1600 Weather Radar System operates primarily from the aircraft's 28 VDC power system.
Power to the control panel is needed depending on which model number has been selected for use.
In addition to the dc power requirement, the system requires roll and pitch output voltages from the
aircraft's vertical gyro for operation of the antenna stabilization system. The associated 115V, 400
Hz power requirements must be in phase with the reference voltage. DC, AC, and vertical gyro
connections to the RDR-1600 Weather Radar System are shown in the interconnect diagrams, at the
end of this chapter.
2.4.4 Roll and Pitch Information
It is important that the connections to the vertical gyro outputs be made according to the system
interconnect diagram, Figure 2.9-8 and Figure 2.9-9. The DA-1203A stabilization servo system
requires a two-wire pitch input signal within a range of 40 to 220 mV per degree. Roll information
requires a two-wire input voltage within the range of 40 to 220 mV per degree. This requirement is
met by most vertical reference sources. It is important to remember that phasing must be such that
aircraft nose down and right roll gives signals at the antenna plug which shall be in-phase with
reference (115V input power to antenna) voltage.
The Pitch and Roll information to the DA-1203A may come form an analog vertical gyro or from an
ARINC 429 AHRS system. If the information is coming from an AHRS system, the ARINC 429
data must be converted to analog data by the RT-1601.
