RADIO ANNOYANCES

Rotorua Morning Post, Volume 2, Issue 408, 17 December 1932, Page 3

RADIO ANNOYANCES

VARIOUS REMEDIES LISTENERS MAY DO A GREAT DEAL TO ELIMINATE TROUBLE SOME PRACTICAL HINTS The prohlems involved in tr.a,cing and eliminating powet surgeis, leakages and harmonic radiations which disturb radio reception receive sympathetie eonsideration from Departmental inspectors; but it is frequently within the seope of listeners themselveg to reduee, if not entirely eliminiate the effects of the various classes of fry and buzz which are the curse of listeners in these affected areas. . . . Correet plaeing of the aerial with respect to the direction from which the interference comes will frequently overcome the effects of the latter. The writer was recently called out into the country to test for power radiation intereference and taking advantage of the directional qualities of the portable test reeeiver used on the job, a direction was found at which to run an inverted "L" aerial which would eliminate the interferenee. A few days later an efficient aerial of this type was 'erected at the angle plotted, and the interference was redueed to a minimum; notwithstanding the fact that the intensity of the buzz with an indoor antenna had heen unbearable. A few hints on efficient ereetion and construction of a good all-round type of aerial may be appreciated. The insulation of your aerial shonld be of the best. Moisture is one of the greatest enemies of good insulation. It should be obvious to all readers of these notes that their aerials must be well insulated, yet the writer has seen dozens of aerials recently which, although well insulated at the ends, have bare lead-in wires touching the metal spouting or roof gutters. Do not let trees touch the aerial system. Bring the lead-in wire as direet as possible to the set. Have the lead-in wire as a continuation of the aerial wire, so as to avoid joints. Ninety per cent. of exposed soldered points in aerial system become inefficient wTithin a few years, as the solder becomes brittle and cracks ; away. The aerial may be up to one hundred and twenty feet in length, including the lead-in wire. There is nothing to be gained by exceeding this length (but noise). Beyond one hundred and twenty feet in length the antenna system fundamental becomes too great, necessitating a fixed and variable condenser in series )with. th'e aerial, of a capaeity of about .0005 to .00025 mfds. If, on the other hand, the aerial is too short, at variometer may be inserted in the lead-in. A long aerial makes for broad tuning, increased volume, and increased noise level. A short aerial while causing a drop1 in signal strength, sharpens up the tuning and decreases the ratio of noises to signal. Choice of an Antenna The average good receiving antenna is a single wire run horizontally between two vertical uprights and a.t right angles to, and as far as possible away from power lines and other sources of electrical interference. It should be placed as high and as free as possible from other obstrucions or metal structures of any kind. As a rule, both the length and the height are controlled by local conditiong and the available facilities, such as chimneys, already erected poles, skylights, etc. The person making the installation should look around and pick the vantage points that most nearly check up with the ideal antenna conditioms before putting up the poles. An Efficient Aerial A highly efficient aerial is erected with' the following considerations in mind: — (1) The overall length from the free end to the ground should not exceed 120 feet. (2) The horizontal part should be as high as possible. (3) It should have no close approach to trees or buildings. (4) Tbe lead-in wire must be kept as far away as possible from trees or buildings, except of course at th'e point of entry to tbe house. (5) The aerial should have an absence of joints, soldered or otherwise. (6) The set should be placed close by the lead-in tube. (7) The wire should be fairly heavy and rigid. (8) All connections should be thoroughly clean. (9) Straight and well-secured aerial masts should be used. (10) The aerial should not be near to, or parallel with other wires or aerials.

The Earth Connection A short and efficient earth syspower interference, and those in aftem goes a long way to overcoming fected areas would be well repaid if they overhauled or replaced their "earths." In the case of a water pipe earth, examine the connection to the pipe, and if necessary, remove it and clean both the pipe and the wire with emery paper. When resoldering, remember that a little solder will make a better joint than a large and heavy blob. A buried earth is usually more efficient in damp weather, but in dry weather i3 is possible for the ground to contraet away from the plate, and this, of course, will result in indifferent, and possibly noisy reception. The connection to the lightning switch or arrester should be periodically iexamined, and the iswiteh contacts pressed in so as to form a tight connection when the switch is elosed in eith'er position. An earthed screen round the set will frequently effeet an improvement, and this is attained by earthing the metal ehassis of present-day receivers. Probahly one-third of the interference complaints are due to reeeiver or antenna system fauls, and if the above instructions are adhered to, reeeiver owners will be able to effect cures themselves.