Lifetime Service

Radio Record, Volume IV, Issue 14, 17 October 1930, Page 23

Lifetime Service

Design of Modern Receivers

[HE life of a radio receiving set has never been determined definitely, though many unfounded conjectures have been made by persons not thoroughly familiar with its construction, Such predictions as were made. varied anywhere from:two to five years, none of them correct when considering a

well-designed. and efficiently-construct-ed receiving outfit. The modern receiver is subject to mechanical wear at only three points, which are: the bearings in the variable condensers; the volume control unit and the "on" and "off" switch. While the parts that are subject to mechanical wear are usually designed to be easily replaceable in regular servicing operations, each unit is selected by the aid of "breakdown" tests to give a lifetime of service. These tests operate the moving parts of the apparatus hundreds of thousands of times, which reduced to years of operation represent a lifetime of uninterrupted service,

The problem of deterioration by moisture entering the radio receiver is of major importance ‘in figuring the life of the apparatus. Of major importance also is the "factor of safety" provided in the electrical. insulation and dielectrics employed in the chassis and the loudspeaker.

Another item of importance in figuring the life of a receiver is the ability of the various resistances to withstand adverse climatic conditions. It has been found by~ field tests that wire wound resistances, for example, must have a conductor size adequate to withstand the mechanical strains of continued heating and: cooling, as well as a vitreous enamelled covering over the wire to seal against corrosion and other damaging effects of moisture. The wiring of the receiver merits

particular consideration with regai4d to soldering, as long, efficient life of the receiver depends on the materials.used in this operation. , While quick and secure soldering can. be done by. an inexperienced worker, when acids or soldering. pastes and solutions are used, it was early found in telephone apparatus construction that these kinds of soldering fluxes were the result of later troubles. Some of these fluxes are conductors for electricity and through creepage along the apparatus terminals or wires cause "cross-talk" or defects in operation.. In: other cases, the paste collected conducting dust which in time caused electrical trouble. Resin flux is probably the best to use.’ .. It is unreasonable to expect a radio receiver to operate efficiently throughout a lifetime without receiving a reasonable amount of attention, any more than one would expect an automobile to run indefinitely without adequate service. Valves are among the most important considerations in this respect. Their occasional replacement should be practised if the maximum efficiency is desired at all times. Hyven one slightly defective valve will have a detrimental effect upon the operation of the set as a whole,