This Ret is intended for those who are making their first radio receiver, or for those who want a simple, efficient and inexpensive set for any purpose It uses a minimum of apparatus and presents no difficulties to the builder. There are no tricks in this circuit and results are sure.
The experimental set was used in New York City with an aerial about 50 feet long on an apartment house roof. Local stations, such as WJZ, WOR, and WEAF. came in with very good volume, and all the distant stations which are ordinarily heard in that locality, such as Chicago, Atlanta, Pittsburgh, Davenport, etc., were received with little difficulty. There are only two adjustments and the tuning is not at all difficult. The selectivity is good and the complete range of broadcasting wavelengths is covered. This type of receiver has an advantage over the ordinary single circuit receiver, in that it causes considerably less interference to neighboring receiving sets.
In the test set a Paragon Variocoupler was used. The number of turns on the stator, or outside coil, was reduced to 60. This winding formed the secondary and was connected to the variable condenser, and the grid and filament of the vacuum tube. Over the secondary, and in the same direction, were wound 10 turns of wire near the end which was connected to the filament. This winding formed the primary and was connected to the aerial and ground. The rotor or inside coil of the coupler was connected on the plate circuit as a tickler coll.
In receiving, the first operation is the adjustment of the vacuum tube. The rheostat is advanced until a hissing sound is heard in the phones, and then backed off until this sound just disappears. It will not be necessary to change this again except to compensate for changes in battery voltage.
The tuning is accomplished by advancing the tickler dial until a soft, popping sound indicates that oscillations have started, and then revolving the condenser until a whistling sound shows that a station is in>tune.
The tickler coil is then moved in the reverse direction until the music or speech is cleared up. A slight readjustment all around will bring the volume up to maximum. The receiver should be kept in the oscillating state for as short a time as possible, as even this set causes some interference to others who may be listening in on the same wavelength.
The location of the instruments and the connections are shown on the accompanying diagrams.
While the layout shows a standard socket, and best results were secured with a UV 200 Vacuum tube. UV 199 or C 299 tubes also gave good results when used in the set with a Na-ald No. 429 Adapter.
When using a UV200 tube a grid leak of 1 megohm was used, and one of 4 megohms was used with the 299 tube. The best value will probably vary with different tubes of the same make.
The following material was used in the experimental set:
1 Base Board 7"xl0"x%"______________________________ «0.35
1 Condensite Panel. 7" x 10" x 3/16"____________________ 2.10
1 Filkostat _________________________________________ 2.00
1 Dubilier Micadon Fixed Condenser. .00025— 35
1 Dubilier Micadon Fixed Condenser. .001 35
1 Pair Na-ald Tip Jack« 25
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