SOME RADIO HINTS.

Taranaki Central Press, Volume IV, Issue 332, 13 January 1937, Page 8

SOME RADIO HINTS.

(Feature Release- of “Spark-Gap” in “The Australian Journal.”) Fixing an Aerial to a Tree. When it is desired to attach an aerial to an unc'.imha.ble tree, the following method, which has proved successful on many occasions, may be tried. A length of thread longer than twice the height of the tree is attached to a suitable missile, such as a half-inch hexagonal nut, and projected over the top of the tree. The thread, which should be of good quality, is then used to pull a strong, light cord, by means of which the aerial may be raised. A Point for Crystal Users. It is a mistaken idea to think that the rectifying properties of a crystal depend entirely upon the kind of catwhisker used. The pressure at the point of contact has a lot to do with the volume of the signals, and many detectors could be improved by paying attention to this point. Sharp Bends; Poor Reception,, Not only should the aerial wire be in as straight a line as possible, without any sharp bends, but this principle should also be practised when building a radio receiver, because high-frequency currents will leave a wire at a sharp bend. Wires carrying radio-frequency currents should not be run parallel, as this •will cause interaction and consequent howling.

To Cure “Popping” Nojses. Regular ticking or popping noises are generally due to faults in the grid leak. Possibly it is of too high a resistance, and the starting and stopping of oscillation then causes the ticking noise. Too much reaction in an effort to bring in distant stations wifi also cause such noises. An Easily-made Dry Battery, An inexpensive dry battery that can easily be constructed by the amateur radio mechanic is described by ‘‘Spark Gap” in th e January Australian Journal. Get a glass jar about three inches in diameter and about six inches high, and into it fit a cylinder of zinc, to the inner face of which a piece of blotting paper has been glued. A terminal screw should be sobered to the zinc to enable a good connection to be made. Place a carbon rod in the centre of the jar, and around it pour in a paste consisting of three parts water, one part muriatic acid, four parts of crushed charcoal, two parts of flour, and one part of plaster of paris. After the paste is in, pour in sealing wax to seal the top of the cell, leaving an opening for the escape of gas. Thp r-pll will hp rp-.arlv for hrp. in

The cell will be ready for use in about three hours after charging.