Radio Broadcast - 1923, August - 86 Pages, 8.5 ... - VacuumTubeEra

338 Radio BroadcastTHE COLIN B. KENNEDY PORTABIcase, however, instead of using \JV-\gg tubes,the 2Oi-A's are found more satisfactory andmay be operated from the automobile or boatstorage battery as described a little farther on.The De Forest four-tube receiver, called theD-io, may be used to operate a loud speakerwith UV-I99 tubes over comparatively longdistances without an antenna, and inasmuch asthe A and B batteries may be carried in thelower part of the receiver cabinet, this outfit isvery practical for .traveling. The necessaryequipment, including the loud speaker, a goodpair of telephones, and a carrying strap maybe had for approximately $225.Where it is desired to operate without antenna,ground, or loop, the new four-tubeGrebe receiver may be used. In this case, asingle wire some twenty feet long, thrown overthe top of the car or across the roof of the deckhouseon a boat, will work very satisfactorilyand collect energy enough for the operation ofa loud speaker over comparatively long distances.Where the auto or boat batteryisused, it is already grounded to some part of themotor and the single wire is all that is necessary.It may be run around an auto top or up themast on a boat.ENTERTAINING A CROWDTOUD speaker operation, as we have con-L/ sidered it so far, is not of the characterthat will entertain a whole community or supplymusic with volume enough for dancing inthe open. This may be accomplished, however,if any good power amplifieris used. TheWestern Electric or Magnavox three-tubeamplifier, for example, used with UV-2OI-Atubes opera-ted from a storage battery and oneio5-volt B battery and a 22^voltB battery in series will beenough to supply music for theentertainment of rather largeaudiences.It isquite likely that mostvacationists will find that receiversoperated from dry cellswill suit their purpose best andthere is little use in discussingreceivers of this character, forthose of standard make are suppliedwith complete instructions.But where the automobile orboat storage batteryis to beused to light the filaments, acertain amount of care must beexercised to prevent the filaments being burnedout, especially while you are in some placewere new vacuum tubes cannot be obtained.In an automobile, plugging in on the storagebattery is a simple matter. Most machinesare provided with a dash light and the wiringsystem is made to accommodate either singleordouble-contact bayonet-based lamps. Bytaking the lamp out of your dash socket you can'determine the character of wiring in your machine.Having found this out, it is but necessaryfor you to call upon an automobile accessorystore and procure an attachment plug fromwhich a pair of wires may be led to supply thecurrent for operating your filaments. In connectingthese attachment plugs, care should betaken to have all the contacts firm. A loosecontact will cause a great deal of noise. Beforeplacing the wire in the attachment plug,it is a good plan to solder the end of eachwire so as to make it a solid mass ratherthan a number of strands. By so doing thecontact screw in the attachment plug will notcut through the thin wires and there is verymuch less possibility of a short circuit. Themost suitable wire for work of this sort is calledSINGLE OR DOUBLE CONTACTThat's the question when you wish to use yourauto storage battery to light your filaments.With one of these little adaptors plugged inyour dash socket you can get "juice" in a jiffy