RADIO NOTES

Rotorua Morning Post, Issue 2, 25 August 1931, Page 6

RADIO NOTES

"Kathode."

V By ■ J \

The tomal difference between an -old and (a modern receiver is very pronounced. An old receiver- may be improvjed in tone by replacing the audio trarisformers with those of modern mariufaeture and by adding a power valjve to the last stage. I When otie valve in a pnsh-pull stage of a receivrer or amplifier has become defective /through .use, both tubes should bq replaeed. To work effici'ently this pair of yalve? must be matchedl. The ^Iverage receiver in Rotorua is capab^of receiving 3YA in daylight durinjg the winter months. As summer , approaches it will be1 noticed that ..'this station will gradually fade out 'until it is not heard during the houits of sunrise and sunset. ■ This elfd'ct will become most noticeable aft^r the equinox. , Though the American stations have been received exceptionally well during the past winter, it will be noticed that they may be logged in greater numbers during the summer, months. The reason is that a transmitter reaches out much further when operating under winter conditions. This summer should he an excellent one for long-distance reception. There are many types of aerials in use, though the L type is the most . efficient. Where. the twin wire type is used spreaders of at least eight feet are essential for efficient operation. Radio reception in Rotorua 'is rapidly changing from winter to summer conditions, and now is the time to give your installation a "spring cleaning." Haul down your aerial and examine the wire. If corroded, invest in a new piece. Give each insulator a good cleaning to remove the leakage paths cau^ed by dnst and corrosion. Clean the earth connection and instal ■a new earth wir,e if the old one is unsatisfactory. Remove dust from the receiver with a small feather duster or camel hair brush arid clean between the plates of each variable eondenser with a pipe-cleaner. New valves are an expensive item, but if the ones you have are getting old, a new set is a good investment. Mr. J. Talbot and Mr. D. Cuthbert were two successful candidates who sat for the transmitters' examination recently held in Rotorua. Radio signals from Rotorua have been heard in every country in the world. This will demonstrate the uncanny carrying power of short wave lengths, when it is recognised that the maximum power used by the Rotorua transmitters is 50 watts. These .signals have been received in France at almost maximum strength. A message bound for New York was handed in to one of the Rotorua transmitters at 7 p.m. on a recent evening. An hour later it reached its destination via the Arctic circle. The transmitter m question had a schedule with an operator near the Nortli Pole, and had the message relayed to New York from there. The construction of radio apparafcus appeals to many and some prefer to build their own receivers. From tim'e to time "Kathode" will describe various receivers and adaptors most suitable for Rotorua conditions. The acoustic properties of a room are often very marked. The receiver should he tried in different parts of the room until the best position for tone is found. In most cases this will be found to be in a corner. Different valves should be tried in the detector socket of a receiver. Some valves even though of the same type make more efficient detectors than others.