RADIO NOTES

Rotorua Morning Post, Volume 2, Issue 332, 20 September 1932, Page 6

RADIO NOTES

dayught reception SUMMER CONDITIONS OF SIGNAL STRENGTH BECOMING NOTICEABLE THE WEEK'S LOG (Notes by "Kathode.") The past week has been fair for radio reception, though static- was rather severe during the weelc-end. Daylight reception is falling off slightly and the end of October should • show a noticeable reduction in signal strength between sunrise and sunset. This condition is quite normal and is caused by an increase in the strength of sunlight. The Heviside layer, when ionised by the sun, loses, to a great extent its reflecting properties. j Increased ionisation causes increased j penetration by radio energy and in- j creased penetration means a loss in 1 signal strength. In non-technical ■ tsrms, the sun, on increasing in i strength, gradually places a mist over the reflecting mirror. As the rays j penetrate the mist they lose power, i and on reaching the reflecting sur- j face start in a new direction only to be once again retarded or reflected back to the surface. The same result may be demonstrated by trying to penetrate a fog with a beam light. The strength of the beam rapidly loses P'ower and the fog shows up as a white wall. This is caused by the light being reflected back by minute particles of moisture in the fog. Several American stations were logged during the week, the best of them being KFI, KGW, KPO, KWKH, and KGO. The second station, KGW, was heard with plenty of volume and was equal in strength to KFI. The best of the Australian stations were 2GB, 2FC, 4QG, 2BL, 2NC, 3AR, 3HA, 2SM and 3UZ. Aerials of enamelled wire are far superior to plain copper or tinned copper for use in Rotorua. The two latter soon corrPde and offier a high resistance to the minute radio frequency currents picked up from transmitting stations. Radio frequency energy travels on the surface of a wire, therefore corrosion should be avoided. Even enamelled wire will not last indefinitely under local conditions and an inspection of the antenc/a should be rnade at least every twelve months. If you are not satisfied with the tone of your reeeiver, try a simple expariment. Place the reejeiver in different parts of the room and note the change in tone. The acoustic properties of a building are often very marked, and there is a "best" position for the set, providing it can be detected. In most cases a corner will be found to be the ideal position. Pirating is prevalent whenever a fee is charged for the privilege of receiving radio signals, and the British Broadcastmg Company have organised staffs, equipped with special apparatus for detecting illegal radio receiv'ers. Illegal transmitters are also frequently discovered and the operators brought to boolc. One case in particular occurred in Paris, when a number of listeners were puzzled by a mystery transmission picked up on 308 nratres. At various intervals it was announced as "The Red Waves." Inviastigations proved that the broadcasts emanated from a private station operated by members of the Communist Party. The French Indo-China short wava transmitter "Radio Saigon" is >easily received in Rotorua and usually arrives with splendid volume. There is a chance that this station will be closed down, as the Governor-Ganeral of Indo-China has declared his inability to continue the annual subsidy. Failing pecuniary help, this station will be forced to suspend its concert programmes. Some valves, evan though of the same type or make, differ greatly in detection efficiency. It is always worth while trying several valves in the detector socket, though, of course, care must be taken to use the same type. It is also unwise to use a 224 type valve in a circuit designed for a variable-mu. The 224 may operatie in a fashion, but the grid bias will be unsuitable and unstability may result. When constructing a reeeiver from a published design, it is well to remem ber that any alteration to the original design may greatly affiect reception.