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Page Title:
Table 3. Contractor identification resistor values. |
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|  MIL-D-70789A (AR)
The voltage outputs shall be within 5 percent of the specified
voltages including the effects of source and load regulation and
ripple. Power supply outputs shall be protected from overloads
and over voltages. The DRU shall not shutoff or indicate a
failure when momentary current surges are required to charge
capacitors, up to 5 microfarads in value, in external devices
being powered by the DRU.
3.5.4.2.2.2
Unregulated.
The DRU shall supply unregulated,
24 VDC, vehicle power for external use. This power output shall
be activated only when the DRU is activated (3.5.4.2.1). The
load power will not exceed 32 watts and the surge current shall
not exceed 2.0 amperes. The DC returns, pins 21 through 23 in
Table II, shall not connect to the DRU chassis at any point.
3.5.4.3 Internal test. Internal wiring and pin assignments
for test connector J3 are at the discretion of the contractor. A
contractor identification resistor shall be wired between pins 1
and 5 inside the DRU in accordance with Table III. J3 shall be
covered by a cap which shall prevent contamination of the
connector pins. The cap shall be secured to the DRU chassis to
prevent loss.
TABLE III. Contractor identification resistor values.
Resistance (ohms +5%)
Vendor
4000
Honeywell
Kearfott
3000
3.5.4.4 Data interfaces. Data shall be transferred between
the DRU and other prime system subsystems (such as CDU, VMS, or
AFCS) via digital (two-state) signal circuits. Data will be
formatted as binary coded digital data (commands and messages);
pulse trains (serial data bus clocks and odometer signals); and a
discrete (travel lock). The DRU shall be ready to receive or
transmit data within 10 seconds of turn on.
3.5.4.4.1 Signal circuits. All signal cirucits, except on
Power Control (3.5.4.2.1) and programming discretes (3.5.8.9),
which connect the DRU and other prime system subsystems, shall be
balanced differential voltage circuits in accordance with EIA
Stamdard RS-422. All line drivers shall comply with the
generator electrical characteristics specified in RS-422. All
receivers shall comply with the requirements of Military Drawing
78020 device type 02.
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