Amateur radio - how and why of wireless with complete instructions on operation of receiving outfits (1922) (14754914651)

Identifier: amateurradiohoww00grai (find matches)

Title: Amateur radio : how and why of wireless with complete instructions on operation of receiving outfits

Year: 1922 (1920s)

Authors: Grainger, Maurice J

Subjects: Radio Amateur radio stations

Publisher: New York : James A. McCann

Contributing Library: University of Connecticut Libraries

Digitizing Sponsor: LYRASIS Members and Sloan Foundation

Text Appearing Before Image:

eing tapped off atabout 18 to 20 volts. Sixty volts is recom-mended for the amplifying tubes. Any good type of audio frequency trans-former may be used. As the amplification ofthis type of apparatus is quite great it is neces-sary to take precautions against internal oscil-lations, or howling. This condition isbrought about through a feed-back of energyfrom one tube to the other. In general, byplacing the transformers as far apart as pos-sible (about six inches), and placing the coresof the transformer at right angles, the troublewill be eliminated. (Fig. 14.) The selectivity of this receiver is very great.It is suitable for continuous wave, or C.W.,reception, with or without shields. The useof shields, however, is recommended. Receivers of this type have been con-structed using the same coil as grid coil andcoupler coil. Where this type of constructionis used it is necessary to loosen the couplingbetween the primary circuit and the grid andcoupling coil. Wonderful results will be ob-

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o en C5 C oo 73 CO E o T3C s-. o ■+-< o o o Q ao T3 S ass-<W)aJ S 6fl AMATEUR RADIO 97 tained where Litzen Draht wire is on allthe forms. Operation will be materially im-proved by keeping the leads to the vacuumtubes short as possible. This is probably the best of the short waveregenerative receiver connections. The cir-cuits must be properly designed, however, inorder to obtain good results. The value ofthe grid circuit condenser (Condenser A)should not exceed .0007 mf., and best practicelimits it to below .0005 mf. To cover an ap-preciable wave-length range, therefore, it isnecessary to design the grid coil very care-fully. This coil may be made variable butit is not recommended. There are hook-ups and hook-ups. Sorapid has been the development of the scienceof radio that they are almost as numerous asthe sands of the seashore. When the timecomes for you to decide upon the circuit youare going to use, it all depends upon the appa-ratus you have at your disposal. Fig. 15 show

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1922

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