The general communications facilities in the B-29 consist of radio and interphone equipment to provide 2-way communication with ground stations and other airplanes, interphone communication between crew members, and the reception of radio range and marker beacon signals.
In addition, the B-29 also carries specialized equipment for automatic radio-direction finding, and the recognition; and identification of friendly aircraft. However, since this is specialized and classifield equipment, it is not covered in this manual. Special publications covering their maintanance and operation are available.
The general communications equipment consists of the following:
1. LIAISON RADIO SET
Receiver and transmitter for operation in the frequency ranges of 200 to 500 kilocycles (Kc) and 1500 to 12,000 Kc which are covered by seven interchangeable tuning units. Two antennas—a fixed antenna and a trailing antenna —are available for use with the liaison set. The right-hand wing skin forms the fixed antenna; a 250-foot wire wound on a motor-driven reel forms the trailing antenna. Either antenna may be selected by operating the shielded antenna transfer switch mounted on the cabin bulkhead above the radio operator's table. Your B-29 may be equipped with an eleven channel AN/ ART 13 set. (See "Standard Procedures for Radio Operators.")
2. COMMAND RADIO SET
The command radio consists of two transmitters, three receivers, and auxiliary equipment. The equipment is short-range, and serves primarily for plane-to-plane communication on the following channels: Transmitters -4000 to 5300 Kc and 7000 to 9100 Kc. Receivers-190 to 500 Kc, 3000 to 6000 Kc, and 6000 to 9100 Kc. The command set antenna consists of half of the wire extending from the lead in insulator at the radio operator's station to the top of the vertical stabilizer.
3. RADIO COMPASS
The radio compass consists of a receiver mounted in the forward bomb bay, control boxes mounted at the copilot's and radio operator's stations, a relay to switch control from one box to the other, an automatic direction-finding loop antenna mounted on the fuselage above the bomb bay, a retractable whip antenna aft of the upper forward turret, and direction indicators on the airplane commander's instrument panel and the radio operator's table. The compass operates on a frequency range from 150 to 1750 Kc and may be used with the loop antenna, the whip antenna, or both.
The whip antenna should not be extended at airspeeds greater than 240 mph.
4. MARKER BEACON RECEIVER
The marker beacon receiver operates on the ultra-high frequency of 75 megacycles (Me). In use, it indicates signals received from instrument landing markers, fan-type markers, and cones of silence, and other ground facilities which employ 75-Mc horizontally polarized radiation. The antenna is mounted below the fuselage between the bomb bays.
The interphone system provides communication facilities for crew members at 11 stations — bombardier, airplane commander, copilot, flight engineer, navigator, radio operator, top gunner, side gunners, tail gunner, and crew compartment. Besides interphone facilities, the system also allows the crew limited use of the radio facilities.
6. IFF RADIO SET
The operation of this equipment is automatic and controlled by switches on top of the airplane commander's instrument panel and at the IFF control box. Two detonator switches are provided next to the airplane commander's control switch. Their purpose is to set off a detonating charge which destroys the equipment if it becomes necessary to abandon the airplane. When you push both buttons together, a small charge explodes in the receiver. There is also an automatic detonator switch, which can be set to destroy the equipment when it is subjected to any severe shock. The IFF antenna is mounted on the forward bomb bay left-hand door.
7. NAVIGATIONAL RADIO EQUIPMENT
This equipment is designed to give the airplane commander lateral guidance during landing operations. It consists of a receiver which can operate on six tuned frequencies (108-3, 108.7, 109.1, 109.5, 109.9, 110.3 Me), a control box, antenna, and an indicator on the airplane commander's instrument panel. The antenna is mounted on the fuselage above the wing.