WIRELESS WORLD.

Taranaki Daily News, 19 December 1924, Page 11

WIRELESS WORLD.

BROADCASTING POPULAR. CONGESTION IN AMERICA, (By “Honeycomb.”) Such congestion exists in the United States at present owing to the great volume oi but partially controlled broadcasting, that authorities there are extending the wave band facilities for wireless telephony. The Bureau of Navigation has authorised the issue of restricted licenses to amateurs to use the bands between 75 and 80 metres, 40 and 43 metres, and 4 to 5 metres for C\V transmissions. Previously the amateur band had been from 150 to 200 metres. Though the present permission is in the nature of an exiperiment the facilities provided on these short wave lengths will give much greater freedom of operation than at present exists, for on t-ne short wave stations can operate with a variation of only half a metre without inttZference. In America, too, as in New Zealand, the amateur is being drawn to investigating the fuP possibilities, of very short wave transmission. USEFUL HINTS. Erect the best aerial and provide the best ear l.i connection you can in your situation. Trying to get good results on a poor aerial is like riding a bicycle with the brake on. A long single wire aerial is the best for amateur purposes, and the earth connection should be as short as possible and lead to permanently damp soil. Use stranded enamel covered wire for the aerial if you can afford it. The corrosion due to salt spray in the air rapidly creates a skin of poor conducting material on bare copper wire, which is almost certainly detrimental.

Do not search for stations with your set oscillating strongly. In this condition it is easy for a carrier wave to be missed. The set should be just oscillating and no more, as in this condition it is most sensitive. The above facts can easily be proved by a minutes testing on a carrier wave. When the wave is heard it will be noticed that as the point where oscillation ceases is approached the strength increases considerably. Theoretically the strongest beat signals will be heard when the incoming wave and the local oscillations are equal in strength. Since the received waves possess very little energy indeed, it is at once seen that strong local oscillations are detrimental. Furthermore, they are a nuisance to other amateurs in the neighbourhood. DANGER TO TELEPHONES. Do not use large variable condensers in the secondary circuit. No greater capacity than ,oW2smfd is really desirable, and even this should not be used all in for best results. If a greater capacity than .0002 mid is found necessary across a secondary a larger coil should be used.

Do not short your telephones across the "B" battery. The windings can be very easily damaged by a heavy current such as would be sent through by a pressure of 50 volts. Supposing that the telephone resistance is 2000 ohms and tlie applied voltage 50 volts, then the current will be 25 milliamps. With the 'phones in an ordinary valve circuit the current through them is rarely more than one to three milliamps, so that the danger of a short across the high tension battery becomes at once apparent. The winding is unlikely to actually burn out; what usually happens is that a breakdown occurs where the insulation is thin, and as a result continuous crackling noises resembling static are heard while the ’phones are in circuit.

A super-broadcasting station is proposed by the vice-president of the American Radio Corporation. His company will erect a 50,000 watt station in New York if no opposing regulations are introduced. Eton the modest one valve outfit should prove capable of bringing in this monster station here in New Zealand. PROGRESS OF RADIO COMMUNICATION. 1921. —President Harding’s message, sent from Radio Central at Long Island, New York, was picked up in New Zealand. This was acclaimed as a new worlds record for distance, 10,000 miles. 1922. —R. Slade, in Timaru, New Zealand, reported hearing numerous American amateurs using power as low as 50 watts. When amateurs attempted to bridge the Atlantic to England they asked the opinion of certain radio engineers, who told them it was not practicable with their small powers and wave length. But the amateur transmitters di<l get over. Now they have bridged the Pacific to New Zealand, and 51M in Texas, using only 5 watts, has been heard in Ceylon, 10,000 miles.

1924.—New Zealand amateurs established two-way communication with Argentine, California, and England. LOCAL RESULTS. On Wednesday, December 10, conditions for DX reception were the best the writer has experienced for some time, and it was possible to work the loud speaker on part of KGO’s (Oakland, California), programme. 4YA (Dunedin) also broadcasted an excellent programme on this night.

2YM (Gislborne) was very poor on Sunday night last, his items fading out completely at short intervals. This station transmits excellent programmes and at times his volume is stronger than that of any other New Zealand station, but the. trouble is that it is not consistent. 'Pronounced fading mars to a large extent most of 2YM’s programmes, but once this bugbear lias been overcome 2YM will be second to none in the Dominion.

I'YA s programmes have been partly spoiled during the last week or so, due to the too close proximity of his wave length to that of 2BL (Sydney). As things are at present, it is impossible to separate the two, and in between IYA’s items 2BL can be heard distinctly. I<t is a great pity this matter has not been remedied. Numerous complaints are being made by listeners-in in all parts of the country. The readjustment of IYA’s wave length should not be a difficult task. and it is to be hoped that steps will be taken to effect an early remedy to the present annoying condition. Many amateurs in New Zealand will •be pleased to hear that Mr. J. Orbell

(ex 3AA Ghri-stohurch) is returning to New Zealand on the Rotorua, which should arrive on January 22. He and Messrs. Bell and Slade have made history for New Zealand in amateur radio affairs.