Show vacuum tubes likely to become paralyzed present daiy diy vacuum tubes or the most part have so called tungsten filaments the action of which even at this late date Is not fully appreciated by the average listener the electronic emission 0 such a filament depends upon the presence of a layer of atoms on the outer surface of the filament unlike the oxide coated filaments found in some tubes the tungsten filament Is not merely coated but permeated throughout its entire maas with the rare element thorium during the normal operation 0 such a filament the thorium on the outer surface Is gradually evaporated reducing the emission current and if this action la permitted to continue rendering the tube short lived however while the heat of the filament serves to evaporate the thorium particles on the sur face it Is also boiling fresh thorium particles out of the mass and up to the surface thus the surface Is being continual replenished just so iong as the filament voltage Is not in creased beyond about 10 per cent above the kaied value this evaporation and replenishing process continues at an equal rate so that a constant laier of thorium Is maintained on the surface hen the filament Is subjected to an however the ev apora alon Is excessive so that the tube con becomes more or les par operating these tubes at sub norm il voltages Is alio liable to par aleze them slowly as the filament temperature Is then so low that tl e process of boiling out the thorium from the interior of alie filament becomes abnormally retarded hence it Is important that tubes with tungsten filaments be operated strictly at their rated voltage radio ieva women radio customers outnumber men buyers the of a recent survey as to men and women customers in retail stores in new aorl city insofar as the survey his special alon to radio Is vory interesting in the twelve types of stores tor which the survey gave figures radio las touched by at least four of the and in three out ot these four the women customers fir outnumber the men as shown by the survey this la of special significance in determining the methods of selling radio receivers in department stores of course the suncy showed that 82 per cent of the purchases were made by women in piano store where radio Is sold to a considerable extent today the percentage of women purchasers was ghen at 78 in electrical supply stores tho percentage of women buyers was given nt 80 this Is distinctly applicable to a radio interpretation in the hardware stores men outnumber the women purchasers 51 per cent to 40 per cent by way of comparison note that automobiles run ca per cent men cus bomers and 41 per women la fact automobile and hardware were the only two in watch women did not outrank the men r ft function of batteries with radio receivers the function of the radio A bata tery is to heat the filaments of the vacuum tubes in the set when the filament Is hot enough it shoots oft an invisible stream of electrons some other practical source of electrons that did not require heat were put into the tubes no A battery would be necessary the A battery is but an auxiliary to the notion of the tube merely furnishing the heat essential i to electron emission and actually has nothing to do with the input or output f of the device the purpose of the B battery Is to provide a pull on the electrons so they flow to the plate of the tube thereby causing a flow of current in the plate circuit which as called the plate current it Is the variations in i the amount of plate current which operate the loud speaker so it Is evl dent that the B battery Is directly necessary the C battery furnishes practical ly no power but the grid element in the vacuum tube at a certain voltage p switched to input side of big radiotelephone the cactus lined earphones go to a dutch telephone operator tor the prize wrong number stunt of the century A resident of the hague picked up his phone and asked for a number in amsterdam according to tireless orld after having hla car filled with the usual number of splitters splutters sp lutters he heard a sayong hello or the dutch equivalent thereof hullo he inquired in this amsterdam ster dam no replied the voice this Is ban boeng on the island of java K the telephone operator had anad twitched the subscriber to the input side of the powerful radio 1 telephone station at eindhoven ciol land which communicates with cavay and other points on the other side of the world that enough to jar a resident of leyden radio new y i S 1 l r V i A |