AERIAL ERECTION

Poverty Bay Herald, Volume LII, Issue 16200, 25 November 1926, Page 3

AERIAL ERECTION

CRYSTAL AND TUBE SETS NOT A COMPLICATED MATTER. Be ores of people have stated that it they had room for, or knew how to erect an aerial they would buy a radio •receiver. The impression seems to be rife amongst novices that the aerial is the most, important part, ot the receiving station, but the erection of a good aerial is far from complicated, and can be done uy anyone with average commonseuse. “1101,” has never yet seen a place where an aerial of either one or two poles could not: be erected. If there is not room enough for two poles, and no other high object can be utilised, then one pole only can Ire used, with a 1 semivertical aerial.

The most suitable aerial for the average set is one from 75 to .150 feet long (including lead-in) and 50 or more feet high, fu order to build such an aerial it usually will be found necessary to choose some outdoor site, though some houses have attics in which a 50 to 70 foot aerial may be easily erected. This latter position is not ' always satisfactory for longdistance work, especially if the houso lias an iron roof. '

It is well to bear In mind that the higher the aerial is and the longer (up to certain limits) the more energy will it pick up and the louder will the the signals be. Height is a more important factor Ilian length in determining signal strength and distance. On the other hand, the longer and higher the aerial the more the disturbing influences, such as static, interference from power lines, etc., which will be picked up. The ideal aerial must, therefore, be a compromise between these two factors. A length of wire from 75 to .150 ft. (including the lead-in) is suggested as the mostsuitable all-round average.

IN THE TOWN. In the heart of the town where tlio installation is surrounded'by a number of sources of interference, a shorter aerial may be desirable. In the country far from broadcasting stations and other causes of disturbance, a longer aerial may be better from the standpoint of the greater volume and distance obtainable. Almost any convenient object, such us houses*, trees, sheds, poles, etc., may be used for supporting outside aerials. Caro should be taken, however, to place the aerial insulators well out beyond projections such, as limbs of trees or the gutters of house roofs. This precaution is necessary to ensure that the effective part of the aerial (the part between the insulators) will not be brought into contact with objects when it sways in the wind. The aerial wire should be stretched tight enough to prevent it swaying in windy weather, Borne little slack must, however, be left, in order to ensure against the wire breaking from over tension. This point should be noted when attaching an aerial 1o trees. A strong spring should be attached to one end of the aerial wire to allow for the tree’s swaying. Only the best insulators should be used in an aerial, and it is preferable to use a string of small egg or shell insulators for maximum, results. In cities a string of about three or four insulators at each end of the aerial is always advisable ns soot collects on them in time and considerably impairs their efficiency.

If you are psing a valve set build the best aerial possible, but with a crystal set a large, long aerial is not necessary. With a good crystal set a wire 35 to 50ft. long'and about 20 or 25ft. high is ample. *

SIZE OF WIRE. There are three kinds of aerial wire on tiie local market to-day: No. 14 bare copper, No. 7-22 stranded bare copper, and No. 7.22 stranded enamelled copper wire. The lasting qualities of each is the only difference; signal strength will be the same all round.

stranded, and for the average installation the bare is quite-satisfactory. The enamelled stranded wire overcomes corrosion in' the cities dr at the seaside. Fabric-covered wire should not bo used, as the sheathing absorbs water when it rains, and the effectiveness is thereby reduced. Soot collected on aerial wires is often blamed for reduction in aerial efficiency. It is more probable, however, that notable reduction in signal strength can, in such, cases, be traced to sooty insulators. The effect of corrosion and soot on the aerial wire itself is by no means so important as its effect on the joint where the lead-in is connected to the aerial. If this joint is well soldered, or if a continuation of the aerial wire is used as a lead-in. without any break or connection, corrosion will not cause any trouble in this quarter. If, however, tin.' lead-in wire is merely twisted about the aerial wire and not soldered to it the connection- may become bad in a very short time.