The Birmingham age-herald., 1922-10-22
BEST METHOD FOR
 HUNTING TROUBLE
 IN THE RADIO SET
Cause of Noise in Receiver Described and Manner of Testing Parts
 Explained
Fly RALPH K. POTTER

 its aerial side and tandem of audio multipliers connected where the head phones had originally been, emts along with it's intensified signals queer squeals and rattling so that quality has been largely saert7 fled for quantity. Producing both quality and quantity in the same set by amplifioation is more of a problem than simply connecting the various clements of the circuits together as on paper indicate.
 The first precaution in laying out set or building onto" one Is to ar range the parts in their proper se- quenee so that connections may be made as short as possible. This is particularly true of all leads to the grid posts of the sockets. To avoid capacity effects the connections 2 should be kept at least a half an inch apart and where feasible the wiring should be crossed rather than . parallel so that only sm Il portions . Sf neighboring conductors are close together. The insulative material used to cover the wires for ordinary house wiring may, if the wires are close together, be of more assistance in passing the high frequency cur rents eXlSt1nB III Il Tddlo Scl tIdu lhN same amount of air space.
 Rigid connections should, wherever adaptable be used within the set so that dropping or accidental displace- ment is not likely to occur. Also the connections must be firmly clamped if not soldered and the functions or two wires should always be timed over and soldered. as twisted con nections are anything but pefma nent Faulty connections at any poiht in the set produce undesirable vari- ations in current flow, which are amplified in the subsequent stages so that they may seriously effect the 4 quality of music and speech produced in the phones.
 Watch Batteries Closely
 single bad "B" battery in a series Is often the cause of disturbances Erratic discharge within the battery itself is the source, and the most practical method of detecting the fanIt is by a process of substitution and elimination. The same may De true of the "A" battery. although this is less frequently the ease providing H is given the proper care. ihe effect in both cases may be reduced bv decreasing the voltage-that Is, by reducing the number of taps across the "B'' battery or cutting down the current to the tube filaments With the rheostats in the A battery ctr- cult.
 Breaks in the fine lead wires to duo-lateral coils, or within the cells of transformers are common source : of trouble The insulation may hold the several ends closely enough to- gather to ft rm more or less contin- uous path of extremely Nariaple re sistance. in which event there will A- .t.Io n Qle tho music from the phones, or they nav be separated entirely so that inc set becomes entirely imperative. The most satisfactory method tor detecting such flaw is tC separate the part under suspicion from the circuit tor at least be sure that there lis no other possible path for the cur rent to take beside that through the .windings) and apply voltmeter, in series with battery of sufficiently high potential to give mid-scale reading on the instrument. across the terminals. If no vt tltage is indicated by the needle of the Noltmeter after pressing down the contact button us- Sllallv provided for completing connec- t;ou through the instrument it is an Indication that the windings are broken.
 Where Break May He Found
 Tn Il coil the break qlT usually be traced to the point where the lead wires are fastened. since here they are subjected to the greatest mechan- ical strain. It may happen that the voltmeter will indicate that the path is complete in spite of the break, but by making all outside connections tight and then moving or jarring the part fluctuations of the needle will assure the presence of a poor contact. The fingers will conduct sufficient electricity to defect the meter needle so that care must be exercised in Keeping the hands away from con ductive parts while making this test.
 less sensitive test which will at lea st detect complete breaks in the circuits of coils and transformers may be made with an ordinary fIashlight bulb and a battery of the bulbs rated voltage. Connections to the bulb should be made through an Improved socket, or its own lamp socket if practicable. With one side nf the bulb socket to side of the battery wires from the other sides of Battery and socket may be attached 10 the coil or transformer terminals The bulb will, of course, light if the circuit is unbroken. Bulbs of large current capacity must not used for this test, as excessive flow of current through the delicate wires Of a trans former is likely to overload them. Both the above tests may be ap- piled to such parts as condensers and socket terminals twithout tubes in place) which should not allow the passage of direct current if function ing properly Indications of flow through the meter or a lighting of the bulb mean trouble" The meter test is, however. the more preferable of the two, since its esensitivity to high resistance short circuits is con siderably greater.
 Adapters Sometimes Faulty
 Tubes that have been fitted with a special adapter base to conform with the design of standard sockets some time cause trouble. One of this type Recently used in the institute 1abora- tory refused to perform properly. When subjected to the meter test it was found that a high resistance cir ruit existed between plate and grid Terminals. While this type of trou- ble is not the most common, it's oc- rurrence is baffling unless one knows what to expect.
 Supposedly hard" tubes that have become gassed by the application of excAssive voltages or were originally below the standard of evacuation will produce all sorts of sorrow when used in amplfying stages. The best method outside the laboratory for de- termining the one which is causing the noise is to cut the phones in ahead of the last stage so that one spare tube is available. and then by 1nterchanging while listening in" on . Broadcast program locate the faulty member