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Blanking Adapter Unit Model BCU-102

Blanking Combiner Unit Model BCU-103

The Blanking Combiner Unit (BCU) provides the capability for the reception, coordination, and distribution of blanking pulses between avionics equipments. The BCU accepts pulse inputs from interfacing equipment and generates and distributes blanking suppression pulses as outputs. The BCU conditions and mixes input blanking pulses in a predetermined pattern for retransmission of blanking pulses to associated receivers. Some of the input to output relationships are reconfigurable at the supplier’s factory. Input blanking signals are received and conditioned by the input receivers. The signals are then combined in a predetermined pattern by the logic function and then conditioned and output via the BCU output drivers. The unit accepts a 28 volt DC input and generates filtered reference voltages to power the BCU circuitry.

BCU Circuit Block Diagram

Blanking Combiner Unit Model BCU-103 Circuit Block Diagram


  • Primary Power: +28 VDC ± 6 VDC
  • Power Consumption: ≤ 4 watts at +28 VDC
  • Propagation Delay: ≤ 400 ns


  • Weight: ≤ 3.5 pounds
  • Size: Depth 10 inches, Width 2.7 inches, Height 6.9 inches.
  • Mounting: 6 each 0.19 diameter through holes.


  • Altitude, Operational: Sea Level to 30,000 feet.
  • Temperature, Operational: -25˚C to +55˚C
  • Temperature, Non-operational: -40˚C to +71˚C
  • Humidity: Per MIL-STD-810E, Method 507.3, Procedure III.
  • Salt Fog: Per MIL-STD-810E, Method 509, Procedure I.
  • Vibration: Per MIL-STD-810E, Method 514.4, Procedure I, and Paragraph with vibration duration of 1 hour per axis.
  • Shock: Per MIL-STD-810E, Method 516.4, Procedure V.
  • Environmental Stress Screening (ESS): All units are subjected to ESS.
  • Cooling: Conduction through base plate.


Input Channel Signal Characteristics Load (BCU Input Load)
1 Active: 15V ± 20%, Not active: 0V ± 1V Opto-isolated within BCU, 900Ω to 1,100Ω
2 Active: > 18V, < 33V, Not active: <1V Opto-isolated within BCU, 1,800Ω to 2,200Ω
23* Active: > 18V, < 33V, Not active: <1V > 20kΩ, See Note
24* Active: > 18V, < 33V, Not active: <1V > 20kΩ, See Note
25* Active: > 18V, < 33V, Not active: <1V > 20kΩ, See Note
6** Active: Open Collector Low,
< 1.3V @ 100mA, < 1.8V @
350mA, Maximum Sink Current
Not Active: Open Collector high,
> 12V, < 32V
Open Collector
7*** Active: Open Collector Low,
≤ +1.5V, Sink Current 30mA Typ.
Not Active: Open Collector High,
+12V to +18V
Open Collector
14 Active: 7.5 ± 2.5,
Not Active: 0 to 0.3V
Opto-isolated within
7 On-Line Active: +15V ± 3.0V,
Not Active: < 0.4V
1kΩ Nominal

* The BCU provides an interconnect path for Channels 23, 24, and 25 prior to any signal conditioning. The BCU conditions the interconnected signal with a load of no less than 20k?.
** Note, Channel 6 is an inverted logic signal.
*** Note, Channel 7 is an inverted logic signal. Signal valid only when Channel 7 On-line signal is enabled.


Output Channel Signal Characteristics Load (BCU Load)
22 Active: > 10V, < +70V, Not Active: < 5V 900Ω to 1,100EΩ
26 RS-422 Levels, Active: Logic High RS-422
27 RS-422 Levels, Active: Logic High RS-422
28 RS-422 Levels, Active: Logic High RS-422
43 Active: 5 ± 0.25V Pull-up through
Not Active: < 0.8Vthrough 500kΩ
series current linit
With 10kΩ load
to ground

Blanking Combiner Unit Model BCU-103 Outline & Mounting

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