Show q t 0 tf 4 IV 11 t T 71 64 S 4 a 4 21 K fw xa awin 3 V a V gorg george 6 W vinal government authority on batteries in his laboratory at the united states bureau of stand ards at washington when a n radio receiver falls to give its customary volume the ill n hat bat are almost invariably fila blamed nied it la Is truo true that they are sometimes the catuso cause of tills this trouble but it Is advisable vl to measure their voltage before arriving tit at tills this conclusion A good make of ill B battery of adequate size should last even with a receiver consuming heavy B battery current for at least six months and if it Is a moderately economical receiver front from nine to twelve months provided it Is given the average wo use of about two hours per day failure to give such life Is an indication either that it Is a battery of inferior make or of inadequate capacity for the set or that there Is a defect in tile re receiver ceLver causes of short battery life briefly tho the factors most frequent ly causing short n B battery life are 1 I 1 audio frequency amplifier not equipped with C battery 2 GI C battery exhausted 8 3 excessive plate voltage 11 4 tubes draw excessive current because of accidental displacement of grid and plate 6 5 ili B battery of insufficient capacity for the drain placed upon it this last cause Is frequently overlooked because the first cost of large batteries Is somewhat more than that bf of small ones hut but it Is indeed a wasteful practice to use a battery of inadequate capacity this Is apparent if the cost Is figured in cent per hour flour of use rather than in first cost on the face of it certainly it seems more expensive to pay about 25 per cent more for a heavy duty ill battery but the economy Is apparent when the heavy duty lasts twice as long in service as the large size battery the savings are even aven greater when heavy duty ill n batteries are substituted for the small portable size batt batteries erlei which are sometimes erroneously used for home hoine receivers there have been cases when ill B battery batary maintenance cost has been reduced from 12 cents in n hour to 2 cents centa an hour by using a heavy duty or extra large ID B battery in preference to one of the portable sizes it frequently happens that receiving set owners replace their ill n batteries when volume falls the slightly increased volume which new ill C batteries give may lead to the conclusion that tin an exhausted ill 11 II battery was the cause of the reduced volume A B battery voltmeter however horev er might show only a normal fall in voltage which would not account for the reduction in volume in such cases it Is advisable to inspect the antenna connections for a broken or corroded leadin lead in loose ground connection workout worn out C battery or lost magnetization of loud speaker unit still another cause of redu reduced ced volume Is the loss of active material on the tube filaments fai fog from the technical news bulletin issued by tile national bureau of standards it dards tubes lose sensitivity electron tubes in radio receiving sets eventually lose their sensitivity this sometimes progresses to tile the point where the receiving set operates very poorly or r not at all even though tile the tube filament Is not burned out the usei user of the set frequently confuses confuse tills condition with that due to an exhausted 11 II battery if the tubes tire of the thor tungsten X L filament type they can usually be re Juven atod to serve as well as new tubes in the receiving set 11 af A simple process of rejuvenation which can be performed at home con slite in disconnecting the ill B battery from rom the ret acet and burning the alia brilliance for a halt half hour usually this restores the filaments to t f activity tiie aie two major causes of reduced volume are exhausted ill B batteries and worn out tube filu filaments ments it la Is easy to td determine which Is responsible for the losi of volume A good I 1 reliable voltmeter will indicate the con dietlin of the ill B batteries if each 45 volt ID B battery registers 34 volts or more the cause of reduced val volume ales les elsewhere probably with the tubes lucli locking in a reliable voltmeter to test B ball orles 3 a good plan Is to have bavo mahand on hand two spare tubes which are known to be in good condition substitute the new tubes for those in the lie set and if tilts tills makes a marked improvement lit in volume it Is 18 tin an indication that the old tubes require reactivation or renewal |