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E. An extremely low noise figure is achieved through the use of a tunnel diode preamplifier.
F. The receiver is a double conversion superhetrodyne. A constant noise level is held at the receiver output by an automatic sensitivity control circuit, which samples the receiver output level just before the transmitter pulse.
G. Antenna stabilization circuits in the R/T consist of operational amplifiers and servos. The operational amplifiers use discrete silicon semiconductors and integrated circuits.
H. The power supply is solid-state, including the warmup time delay circuits. The power supply and all control circuits use silicon-controlled rectifiers, reducing the number of relays required.
4. R/T Mount
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A. AT ALL; AZ ALL EXCEPT 281-299; LH ALL EXCEPT 082-099; IB 406-499, The R/T mounts consists of a dual mounting shelf for the two R/Ts, mating quick-disconnect electrical and waveguide fittings, a rotary waveguide switch, dummy load and rf feeder waveguides between the switch and R/Ts. Two holddown clamps secure each R/T to the R/T mount.
B. LH 082-099; AZ 281-299; AF 157, 161, Two single R/T mounts consist of a mounting shelf for each R/T and mating quick-disconnect electrical and waveguide fittings. The waveguide switch with dummy load is mounted to one of the R/T mounts. Rf feeder waveguides are connected between the R/T mounts and the waveguide switch and another waveguide goes forward from the waveguide switch to the antenna.
5. Waveguide
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A. AT ALL; AZ ALL EXCEPT 281-299; LH ALL EXCEPT 082-099; IB 406-499; The X-band waveguide connects the selected R/T from the waveguide switch to the antenna. A flexible waveguide section is connected to the waveguide switch and then rigid sections extend forward and pass through the pressure seal into the nose randome area. In the unpressurized nose radome rigid waveguide sections are connected to a final flexible waveguide section that connects to a top-mounted waveguide flange on the antenna.
B. LH 082-099; AZ 281-299; AF 157, 161, Flexible waveguide sections are installed between both R/T mounts to the waveguide switch. From the waveguide swtch rigid sections extend forward and pass through the pressure seal into the nose radome area. In the unpressurized nose radome rigid waveguide sections are connected to a final flexible waveguide section that connects to a top-mounted waveguide flange on the antenna.
6. Indicator
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A. The indicators are self-contained and require no power from the R/T units except for control signals thereby enhancing reliability and assisting in fault isolation. Silicon solid-state devices are used exclusively in the sweep and video circuits.
XA B. AZ 201-224; AF 157, 161,
EFFECTIVITY
AT ALL; AZ ALL; LH ALL; CONFIG 1 AF 157, 161; ATG Page 7 IB406 THRU 499 Sep 25/94
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the indicator has a 5-inch display storage cathode ray tube which provide for direct viewing under all ambient light conditions. The brightness of the display is manually adjusted with a brightness control automatically held to the proper level through the action of a photocell mounted on the front panel. Controls allow for viewing directly ahead or choosing left or right offset displays.
XA AZ 201-224, The ranges are 30, 80 and 180 miles. AF 157, 161, The ranges are 50, 100 and 200 miles.
XA C. On AT ALL; IB 406-499; AZ 231-280; LH ALL, the indicator has a rectangular display cathode ray tube which provides viewing under all ambient light conditions. Controls allow for viewing directly ahead displays of 25, 50, 150, or 300 miles on AT airplanes and 30, 80, 180 and 300 miles on AZ, IB and LH airplanes. The brightness is manually adjusted with a brightness control. A SCAN/HOLD control (if provided) allows the video on the display to be fixed (not updated) in the HOLD position or to be updated normally in the SCAN position. Through a process of digital integration in the indicator, sensitivity is improved and random noise and interference signals are reduced. The display is nonfading and holds the video displayed until updated by the next scan.
D. LH ALL; AZ 225-229; 231-299; IB 406-499, the indicator has a 5-inch display color cathode ray tube (CRT) which provides for direct viewing under all ambient light conditions. A BRT (brightness) control adjusts the video intensity of the CRT and a range switch allows selection of 30-, 80-, 180-, and 300-mile ranges on the display.
7. Antenna
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A. The antenna is mounted on the airplane bulkhead behind the radome in an unpressurized section of the airplane. It is used for both transmitting and receiving for both receiver/transmitter units.
B. The antenna is stabilized by stabilization circuits in the antenna and R/T unit. Airplane pitch and roll signals are supplied from the INS to stabilize the antenna in tilt (| 25 degrees) and roll (| 43 degrees). The antenna can be manually controlled from the pilots' control panel to any position of beam tilt between 15 degrees above and 15 degrees below the horizontal.
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