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REGULATIONS
FLIGHT
Section 3251 ADF AND LOOP RECEIVERS
B. Limitations and Precautions in the Use of Loop Equipment (Cont'd.)
b. Adcock Type Range Station - Because of the requests were many for a type of station with simultaneous range and voice, the Adcock type station was developed. This station has 4 vertical towers 120 feet high placed at each corner of a square 600 ft. on each side. Each pair of diagonal towers will produce the same figure 8 pattern as obtained by the loop type station. There is also a center tower broadcasting as a conventional antenna. The carrier on the center tower is on constantly and all voice communication is transmitted over this tower. If atmospheric conditions are good, the Adcock type station is ideal to work with the loop equipment as its effective power and stability is far superior to the Loop type station.

NOTE: There are a few Adcock type stations without simultaneous voice facilities operating in the United States area. The experience with them has shown that although they have the effective range of the conventional Adcock station, the needle of the ADF will wander and hunt when tuned to them in much the same manner as when tuned to a Loop type station. Use caution when using the loop equipment with this type station.

5. Thunderstorm Effect - In flying in thunderstorm activity, the loop equipment becomes practically useless since the lightening flashes and static conditions cause the needle of the ADF to oscillate and rotate with a violence found in no other disturbance. The needle will have a tendency to point to the source of each electrical disturbance whether a lightning flash is occurring or not. When continuous lightning is prevailing, the needle will give no indication of the direction of a station tuned in but will wind and swind continuously. If the aircraft is a short distance away from a thunderstorm, the needle will point to is at every lighting flash. Even a distant thunderstorm will attract the needle to some extent so caution must be exercised in using this equipment in the vicinity of thunderstorms or potential thunderstorms.
6. Aurora Borealis - When Aurora is reported, static conditions may occur and prevent aural reception with the equipment. The needle, however, will remain fairly stable unless the aurora is intense. Under this condition, the ADF needle may have a tendency to weave unsteadily and hunt. Communication and broadcast frequencies are effected, and last will be the very high frequencies. In the northern regions, aurora may be so intense that range stations may go completely out except in the immediate vicinity of the transmittor.
2/1/47 Flight