A unicontrol high-frequency radio direction finder
Francis W. Dunmore · Scientific Papers of the Bureau of Standards · 1926
Tlic Bureau of Standards was asked to develop for the United States Coast Guard a simple type of radio direction finder which should function on 2,100 kc (143 m).Such a device enables a ship equipped with it to locate another ship readily.This paper describes the development of such a direction finder and its installation on a Coast Guard patrol boat.The direction-finder coil consists of four turns of ignition cable wound on a 20-inch frame.It is installed over the pilot house and rotated from below.A tuning unit and cou- pling transformer have been designed so that the direction-finder coil may be used on the ship's receiving set without changing its tuning adjustments, which are locked in the 2,100-kc position.A special form of automatic balancing con- denser operated by a special cam rotating with the direction-finder shaft is incorporated in this instrument .whereby a clear minimum may be obtained at all angular positions of the coil without manual operation of the balancing condenser.The controls necessary when taking a bearing are thus reduced to one-that of rotating the direction-finder coil to obtain the minimum signal.