WIRELESS WORLD.

Taranaki Daily News, 27 September 1924, Page 12

WIRELESS WORLD.

NOTES AND HINTb. LATEST DEVELOPMENTS. (By “Honeycomb.”) Do not burn the thoriated filament, tube at too great a brilliancy. Do not turn up the filament rheostat above normal. This will force too much current through the filament and release the electrons so fast that the filament will become “run out” of free electrons 'in a short time. The filament will burn til right, but there will be little or no .ignals. The correct current Tor the : u V-201-A. or the C-301-A is i ampere. If your tubes are of the type mentioned above and they have stopped working, and still the filaments appear to be in perfect condition, you can bring* them back to usefulness by burning them at the correct filament current (i ampere) for an hour or so without the “B” battery being connected to them. This will cause a redistribution of thorium atoms around the surface of the filament which will again start and maintain the requisite stream of electrons for proper operation. RADIO FREQUENCY TRANSFORMERS. The best radio frequency transformer at the present time is of the aperiodic type. With radio frequency, if the incoming signal is amplified to double its normal voltage, the strength of the signal from the detector tube will be four times as great as before. One stage of radio frequency as. a valuable addition to a set. An ultra selective method of radio reception with radio frequency amplification lies in the use of tuned stages. This method is recommended and preferred for broadcast reception. The best type of set to sweep all wave lengths is the three-coil Armstrong Regenerative receiver. One stage of tuned radio frequency can be added to this set, but the radio stage is limited in effective wave length range unless separate inductances are employed for each band of wave lengths.

A good many things may happen to a receiving valve, some of which may rather puzzle the user if he does not know what symptom to look for. A comparatively rare occurrence with valves of good quality is a -considerable softening of the vacuum within the bulb after a period of use. This happens, as a rule, because the plate and grid, as well as their supports, have not been properly cleaned up in Die process of manufacture. All metals contain certain qualities of occluded gases which are given out under the influence of heat. In a well-made valve the process of bombardment and of cleaning up are so thoroughly carried out that the occluded gases are driven off, with the exception of the minutest traces, which are not sufficient to make any marked difference to the vacuum. But lif you examine a cheap foreign valve I carefully you will see that the inner [ metal parts are dirty looking. This means that the cleaning-up process has not been very thoroughly carried out, and there is a distinct possibility that, when the valve is under use, the occluded gases will gradually be given out.

BOOM IN AUSTRALIA. Radio over here is really marvellous, writes Mr. Charles E. Forest, of the International Radio Company, from Syuney. He says: “Sydney at the present time resembles nothing so much as the world gone radio mad. What may be termed a cult of the crystal is daily attracting a great number of folks; in fact, it seems that the artists’ ball, ma jong, golf, bridge (and, if we may mention it within shooting distance of the above pastimes for the elite), the old and venerable game of two-up, are being rapidly deserted for the new and fascinating hobby of tickling the galena.” The Rev. Bryan King, of Dunedin, an enthusiastic listener-in, reports that, using one valve, he follows the words and music from KGO quite clearly. He states that he heard the announcement from KGO that the power of that station had been increased to 5000 watts. KGO is now transmitting up till 8.30 p.m. on Tuesday, Wednesday, Friday and Sunday evenings New Zealand time. From the writer’s experience rhe noise KGO makes at present certainly appears to be the result of extra power. With a 1000 watts he would nardly come the distance he does with such volume. Air. Allan Evans, of 209 Taranaki Street, Wellington, advises that he has been granted a grade 11. amateur transmitting and receiving license, call sign B2J. He would like any listeners- in at a distance who may happen to hear him to drop a line reporting strength of sigs, modulation, etc. “HOWLING” TROUBLE.

Since the installation of the highpower ©tatioiis in Sydney the “howling” nuisance has been greatly minimised. Since signals are so strong reaction 'becomes almost superfluous and consequently the signals are not generated. This condition will no doubt obtain in New Zealand when we have more powerful station©, But even then it ifi probable that in the most isolated districts the howlers will be a nuisance. It seems to be a case of two evils. If you are near a big station the howlers will not interfere, but, on the other hand, you will find it difficult to tune on the neighbouring station if you are after more distant game. If you are in a district at some distance from a highpower station you will have more choice, but you will be troubled with howlers, since reaction will be necessary on almost every station.—“ Grid” in the Wanganui Chronicle.