Show I I 17 1 r Lz 01 How to Test Old Tube Make Your Own Tester Sometime In the experience of or set 0 owners ners the question occurs D Di my tubes need Dell replacement or coa lion 1 The signs that lead lend up to the question are well known Distant sta ions no longer come In with Uh their customary i late lite current le- le le-comos le comes smaller maller and smaller ugh the n B and amid C remain un on changed The Zhe of ot local stations station begins to ebb All of or which in lint liat tl ll lie e c time I has come Co for a diagnosis to how he heh Melly 1 h idly worn orn the th lie tubes lire are This I can t te Ie o clone don I 1 I i lieu 11 e u a L t t or a tube test lest tester lester tester er which Is not Dot to make maJe Only four Items are arc necessary rint t a abase abase base from nn an old tube second a tul tut e c soel socket ct a II and C fourth fourtha a few fen feet of ot lIe cable to 10 form the lead leads The leads lends should I le I e soldered t t t J the Inida of the lie old oid lub tull base and the c Cre terminals of nf oftie oftie tI tie e socket codet The should to Ie connected In series with the plate pl lead mal lag Ing all 1111 Ir ng enough co that the old tube I t use ace may I e Plu plugged Into nn an socket of ot tic tle set Ie letting leu 1 In Ing 1111 Ito and socket of oC the llie tester sit II sitting ting Ung con conveniently near a II should hould I be used In place of n I 1 I ut at practically It has been found fe that W e voltmeter SU sines SUes es the par pur purpose pose because of 01 its It t two tI I one scales scales one ot of 10 i toils oils and the other of or 7 1 75 r oils lie 7 75 t c it e-it range has lias u a resistance or of iA 10 ohms which Is b relatively snail small compared to the plate pinto resistance It ItIs itIs ItIs Is tills range that Is used as ao n a meter Since very sery ery few tul lul cs ee tai tal e emore emore more than thOD 10 milliamperes late current cur current current rent this tills voltmeter Is Urge enough nouh for practically nil all requirements Before making tests upon any tubes use ue the to 10 obtain the lila ilia ment an the n B and ond C C Then Insert the meter In Inthe inthe the tube tester c t l lul l I place pill the tub tube lu la the socket und and plug the oil ell tube base Into the s socket clet In the radio set The meter Indication Is proportional to 10 the plate current and since 10 roll mil Is considers 1 1 I as full scale deflection It is eay ea y to estimate the correct plate current It If for e the scade searle reading Is then the cor corresponding corresponding responding milliampere reading will be beG beG G 6 If It the lie plate current curr nt nt Is lower loner than 90 40 per cent of ot that gl given gln n by the tube manufacturers manufacturer s data dad for the same II B Band and C volts the tube should hi be bp replaced re- re replaced re replaced placed If the tube Is of the type t pe such as the U U 01 01 1 It can be |