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RADIO AGE for February, 1927
The Magazine of the Hour 25
Building BrowningDrake Power Receiver
Qualify Reproduction Assured With Compact
RADIO'S public today, whether it be the experimenter or the listener, has become quite fastidious in its taste for quality in all forms of reproduction. With the improvements made in the nature of the programs broadcast last year, the radio set has become almost a vital necessity in the home of the music lover as well as the individual who keeps track of news developments via the air. The receiving set described in this article is designed so that its reproductive powers will be readily appreciated by the severest music critic. Considerable care has been used in selecting the proper apparatus so the finest musical performance will be obtained without sacrificing the other elements for successful reception. From the standpoint of simplicity of construction the BrowningDrake design was used, since this arrangement is deserving of, rather than in need of, publicity. For over two years this design has remained unchanged and has gained popularity constantly because of its ease of construction, comparatively low cost and efficiency of operation in service.
By J. E. COOMBES
One stage of neutralized radio frequency amplification is used with a regenerative detector, thus getting all of the energy possible out of a small number of tubes. As for selectivity and distance getting ability the receiver is quite commendable, but it is primarily for its freedom from distortion in the radio frequency and detector circuits that it has been selected for use as a self contained power operated receiver. The only deviation from the standard Browning-Drake construction practice is the introduction of an optional antenna inductance for greater selectivity. This inductance consists of from two to four turns of insulated wire wound on the outside of the antenna • coupler at the filament end. One end of the extra coil is attached to the common ground-filament connection while the other is brought out to an additional antenna binding post. This reduces the coupling from the antenna to the secondary of the first coupler and sharpens up the tuning considerably. This was done for work in Chicago where the average experimenter and listener is beset with two
dozen or more broadcasting stations. In sections removed from metropolitan districts there will not be the necessity for the added antenna coupling since interference there will not be anywhere near as bad as in the city. If it is desired the added antenna coil may be left on and the degree of selectivity governed by changing from one binding post to another as conditions warrant such a change.
Reason for Power
POWER amplification requires but little introduction to the radio public for no single feature of the improvement of the methods of reception has earned more publicity from radio magazines and journals than this comparatively recent development. The reason for power amplification is not difficult to find. Bass notes require a considerable expenditure of energy if they are to be amplified faithfully. When we reason back and realize how much more mechanical energy it takes to sound the pedal diapason of the organ than the note of the violin it is not hard to appreciate the fact a correspondingly