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The CB-3 Receiver is a navigational instrument for use on Radio Beacon static of the Department of Commerce. It is designed primarily for private and commercial pilots, in ships where weight of equipment is of the utmost importance. The receiver operates on the conventional antenna for beam flying, and also in connection with a loop antenna for radio-compass navigation. Pilots can get all weather reports and forecasts with landing instructions and other information necessary for safety in flight, from any of the beacon stations or the control towers on the different airports. The receiver is a five-tube Superheterodyne of very high sensitivity, similar to our Beacon Receiver fully described in Bulletin B-3, except that it has a toggle-switch between the two control knobs on the front panel which cuts the beam antenna in whenever the loop is switched off. The receiver is designed for mounting behind the instrument panel, and the 3" dial has the same general appearance as any of the other flight instruments on the panel.

[[image - photograph of an aircraft with a loop antenna]]]]

The Loop is mounted outside the cabin with the calibrated dial control inside and over the pilot's head within easy reach. This indicator is calibrated in degrees from 0 to 180 with the divisions 10 degrees apart reading from 0 to the left in red, and from 0 to the right in black figures. The dial on the receiver is graduated in kilocycles from 194 up to 420 in divisions of 5 kilocycles each. Volume control knob is on the left and also includes the "on" and "off" switch. The right-hand knob tunes the receiver to any of the beacon station frequencies published in the Department of Commerce within this range. The volume control on this receiver is one of its most important features from the standpoint of navigation. When flying on beacon signals, this control must be kept at the lowest possible "comfortable" volume output. High sensitivity of volume is very necessary for the sharp definition of the "Cone of silence" area above the beacon station near the airport. It is also a very positive indication of whether the pilot is approaching or flying away from a station when distant even as much as one hundred miles. Due to the geographical location of the beacon stations, the necessary range of reception of the receiver on beacon signals is never more than one hundred miles, but the range of reception for weather reports must be two or three times this distance on important or key stations, because the pilot making a trip for five hundred miles or more, cannot always get his weather for the proposed flight from the regular weather report sequence of the nearest beacon station. For this reason, and also because receiving conditions of the average beacon station are very often reduced to a low minimum, this CB-3 Receiver has been given great sensitivity. 


Licensed under Patents of America Telephone & Telegraph Co. and Radio