CURING SICK RECEIVER

Shannon News, 5 August 1927, Page 4

CURING SICK RECEIVER

First aid treatment for "sick" radio sets'that will enable,the man who has only a slight knowledge of radio to lecognise the trouble and make the necessary repairs was prescribed by Lee Manley and W. E. Garity at the meeting of the American .Institute of Radio Engineers recently. They pointed out that the sets do not go bad of themselves. The failure usually occurs while some operation is taking place, such as plugging in the loud speaker, turning the condensers or making a change in battery connections. If the set has been in operation for a period of six months or a year the possibilities of trouble will increase. If the failure has been gradual the first thought would bo that the tubes were worn out. If the breakdown is sudden, a mechanical failure might be expected in one of the movable connections or pigtails, or a transformer may have burned out. If the trouble is due to a noise condition, the failure may be ascribed to dust or dirt accumulations on the condenser plates or other important parts of the receiver. The defect might also be due to a corroded soldered connection. It will require, as a rule, a rather long time for a soldered connection to corrode to such a degree as to caus e this condition. The local atmoapheric conditions under which the set has been operating may have some bearing on the cause of failure. If the set has been operating near the seashore and has been subjeted to the action of salt atmosphere, sufficient corrosion may have taken plac e in the connections or other metallic parts to introduce high resistance or leakage paths. Moisture may saturate the cheaper grades of insulating material to such an extent as to cause high-frequency short circuits. If a set has been operating for a long period of time and has given satisfactory results and then develops noises^and scratching sounds one should' not look foe. a loose connection in the-wiring of the set, but rather for an open circuit in moving parts. Worn mechanical parts are often mistaken for loose connections in the wiring. Th e wiring is absolutely stationary and it 1% not" likely that it will b e disturbed in the ordinary use of the set so as to cause a failure sue to a loose connection. Vernier drive-shafts and vernier plates will wear loose, and while apparently they are making perfect contact to the metal surfaces of the condenser,

still when the set is brought into a

critical condition, as is the case when receiving distant stations, noises will occur that might bo thought due to a loose connection in the wiring.