Show portable that Is 0 OK K for camping two T tube u be set that affords satisfactory range ranga on the earphones by HOOD in radio world the camping spirit is in the hie blood and those who feel alie lie call of back to nature tire arc planning their trips trip and anc deciding on oil their equipment one ol of the first things that most of tile them will decide to take along Is a portable radio set that Is now as important as the lie pun gun the fishing rod and the tent equipment A radio set that Is to be taken along on the trip to the woods must have one thing in common with all the other equipment it must he be light in weight this fact precludes the use of storage batteries for heating healing the filaments of tile tiie tubes in the set dry cells must be used and consequently dry cell tubes must also lie be employed in it the receiver the question of liow how many tubes to incorporate in tile the sot set Is settled by the lie required sensitivity or distance getting requirements of the set that in turn is determined by the distance the camper intends to go from a brond broadcasting casting station there are now so many broadcasting stations scattered throughout the country that it is not possible lle to go outside a radius of 0 about LOO ah miles from one station without being within that distance from some other sta station on hence the set should be sensitive enough to receive the signals from such a distance headset reception since a loud speaker cannot very well be taken along on oil a very lightly equipped trip reception may he be confined to headset operation that requirement qui rement in turn puts a limit on the number of tubes necessary in the set A two tulie tube receder employing dry ell cell tubes and using regeneration ills fills the 00 00 I 1 fig 2 showing a suitable layout bill quite satisfactorily as to sens sensitivity 1 I portability and headset heads cit volume A loop ij in fig 1 1 Is used for inducing the minute ether wiggles to enter the set tills loop should lie v wound to tune the hie broadcast band with a mad cond condenser cl the loop pop preferably should he wound on a large larg frame to make it sensitive but a large loop Is iq not readily portable unless of if the folding variety loops of this type chih which fold up into a iery small ax anil neat deat package can be purchased in most radio stores the loop can also be made by the camper bir himself with the llie exercise ot of a little ingenuity the essentials of a loop are about 00 90 feet of flexible wire 11 and nd to hold this wire of course the llie triune frame must not be made of metal as this will absorb some borne of the llie energy that must he be conserved tor for llie lie tubes dry wood Is good material in a pinch the lie wire can be wound 0 r round n und a wooden box the coupler between the two tubes Is a three circuit tuner or of standard m make a ke it Is best to purchase one of alio abc smaller r types which many manufacturers rs make since space Is an iiii port lint consideration in a portable set since the lie circuit Is regene rathe a high degree sensitivity coil can be obtained b the secondary coil la 12 of the coupler should he be wound so that it covers the llie broadcast hand with a 5 mad fit con condenser dener ca tile grid condenser CS have a capacity of from nicil to a ifil the smaller value gives a greater sensitivity on weak signals and li is sometimes to be preferred over the larger standard value the bypass condenser cl should have a value of na wa mad use 33 volt tubes the tubes best suited to this receiver tire are the 33 volt CO 60 ampere tubes known as the 00 09 ape with willi these tubes tile the common rheostat RI III should have a resistance of 23 25 ohms this will afford adequate volume control as well as filament voltage control the the filament voltage can be obtained from three no 6 dry cells these will give service for a considerable time if extreme Is necessary it la Is even possible to dispense with one of 0 the dry cells but the two used anut be replaced more frequently than if i three are used it is een practicable to uie ue ui e three smaller dry cells such as 4 aa volt C batteries the plate battery need riot not exceed emceed 45 volts and this can call be supplied by one of the small battery blocks obtainable A couple of synill 1 2 ou olt batteries can lie be use used the headset used us ed should haiie bae a high impedance because the impedance of the detector tube Is quite lilyh matching of impedances for greatest power output Is of significance here since the detector tube delivers power in tills this case and not merely voltage A suitable layout of 0 the panel la Is shonn in fig 2 tho the loop terminals are connected conned oil to two phone tip jacks placed in the lower left land hand corner of the panel the audio output from the set Is taken out by connecting the headset to a similar pair of midget jacks placed at the lower right corner tile the rheostat is placed centrally between the tuning condenser dials the size of the panel need not he greater than inches and may be smaller A small baseboard will be needed for mounting the two tubes this can be a small strip of thin wood or hard rubber of suitable size tho the entire set can be mounted in a ery small suitcase the lie set proper at tile top and the batteries tit at the bottom list of parts ione I L one loop made of about 00 feet of flexible wire cl and ca two tao tuning condensers of mad capacity LI 12 12 13 13 A small three circuit tuner to fit ct condenser ca CS one to mcd fixed grid condenser ca one mad bypass by pass condenser NI ill one 25 ohm rheostat two phone tip jacks four binding posts two dials two trox X sockets A small baseboard and a small hard bard rubber panel two 99 tubes three no 6 dry cells forty five volts of B battery one headset A suitcase or other container for set |