ACCUMULATOR FUMES.

Auckland Star, Volume LX, Issue 39, 15 February 1929, Page 16

ACCUMULATOR FUMES.

Now that =o many all-in cabinets (including portable sets) nro schemed, it will h<. as ,- cl ] t0 war ~ readers against the bousjnj: of the accumulator in the same receptacle as the set. No doubt many have at some time or other incorporated an accumulator in the cabinet of the set and noticed that after a few months have elapsed the metallic parts of the receiver assume a dull, dead appearance. Thi* is due to the acid fumes given off by the accumulator during discharge, which, being moist (spray from the electrolyte) are in a very active state to eat into a metal for which they have a weakness. There appears to be no remedy for thiwhen an ordinary lead-acid type of accumulator is used, but in the very near future it is highly probable that the metallic parts sold will be plated with a metal that will effectively prevent such corrosion.

This element is chromium, and research during the last few years has Been very intensive and fruitful, eo much so that the process has been improved and established in industry.

The value of the plating process from a wireless outlook is the complete ability of the metal to withstand corrosive vapours. Irrespective of the fact that an accumulator may or may not be incorporated in the cabinet of the set in close proximity to the delicate wireless parts, the atmosphere in all larse towns and cities contains an appalling amount of acid. This is not poured out from chemical factories only, but from the domestic fire, and so it would seem that all wireless equipment is liable to corrosion unless efficiently designed to withstand it.

THE COPYRIGHT QUESTION. Last year Xew Zealand was represented at the International Copyright conference in Rome by Mr. S. G." Raymond, K.C., who lias now reported to the Government upon the scope and work of the conference. From a resume of this report, published in the "Radio Record," it is gathered that the main achievement was the granting to each country represented the freedom to impose conditions in granting copyright, whereby the interests of the public in the use of musical matter shall be preserved. In fact there is power, on ratification of the conference's resolutions by each Government, for the compulsory supply of copyright matter, with due payment therefor. This will prevent extortionate demands, or the complete withholding of any musical work from being broadcast.

THE THREE GREAT POINTS. A receiver of merit should possess sensitivity, selectivity and a really good tone, by which i= meant clarity a? -well as rotundity. Volume is really a fourth consideration, because oiice. a set has been tuned np to give tone power, in one of the many possible way.*, can be increased. Sensitivity is a factor that count?, for this niran? range. It can be secured by seeing that rectification is as near perfect as possible, by using judicious reaction, anil, sometimes, by increa--ing the plate potential of the detector and lI. F. valves.

.Selectivity is a matter that conevm.the aerial system and the tuning gear. and often exerts an influence on tone because an ultra-selective circuit is always working- on a tuning "peak." to over-run which, or to almost but not quite reach which, will utterly ruin signal quality.

Rotundity is .1 matter determined by judicious ]<>»v-frof|ii'.Miov amplification and the u>o of Miitahlo roervoir across the output. It is possible to make reprodin-i i.<n >o rurmd and mellow as to make ~;.eeeh unintelligible. The happy operator i? he who take? such pains in his experimenting as to strike a convenient medium in all tilings. and this can only he done by dev«>tiii2 tim» and patienee in timing up the wjii->)i> circuit so that it ultimately provide* the result de-iicd.