2FC ON SHORT WAVE

Radio Record, Volume I, Issue 16, 4 November 1927, Page 10

2FC ON SHORT WAVE

SPECIAL, TRANSMISSION. Experimental iransmission on 28,5 -tmetres was conducted from 2FC ‘Sydney on Monday last from 6,15 a..m ‘to. 7.10 am., New Zealand time. A ‘specially good programme was submitted for reception in Britain, Camada, pand the United States, reception in Wellington being at splendid toudspeaker strength. The test was arranged by Amalgamated Wireless fA’sia.}, Ltd., and was also transmitted -on 442 metres for the bertefit of Aus‘tralian listeners,

Radio stages of amplification, added to a detector valve, will oscillate, due to feedback from the plate to the grid circuits of each tube, due to capacitance between the elements of the tube. The use of a neutralising condenser is to neutralise the effect. This allows of the radio stages being worked almost on the point of oscillation, which is the point of extreme sensitivity. Stations then come in without heterodyning. Should regeneration be 1ntroduced into the detector circuit, a greater signal strength will be obtain. ed, but the quality of the signals will not be as good. ‘Thus for purity of tone one should exclude regeneration | from a circuit using a sufficient number of valves to bring the volume of signals up to normal. | If a variable condenser is used in the primary circuit {the aerial circuit) of a receiving set, it is best to connect it on the ground side of the primary winding, with fhe rotary plates attached to the ground binding post, so that body-capacity cffects will be minimised. The rotary plates of the secondary variable condenser should always be conuected to the filament of the valve, never to the grid, for the same reason, There are approximately 90,000,000 people who now receive radio programmes, according to a report made to Secretary Herbert Hoover by Lawrence D. Batson, of the Electrical Equipment Division of tle United States Department of Commerce, About 18,000,000 sets are used. At least 200,000,000 sets wonld be necessary to serve all the peopde, there beng five persons to every set.

SUR Lead ore (Galena) has been used successfully as a rectifier of radio frequency impulses ever since the beginning of radio, and it is still in use. ‘This crystal is extremely sensitive, but will uot retain adjustment when detecting a large signal voltage; thus, this crystal is exceptionally good for the rectification of weak impulses. This crystal wld be used where signals are weak. The application of the catwhisker should be light, as a heavy pressure will prevent it from rectifying. } A representative of the recent New York radio fair said that great interest was being shown in radio parts, revealing that many listeners expected to build their sets during the coming year. The smallest details of both sets and parts have been the subject of unusual attention by the younger generation of show visitors, he said. Australian broadcasting stations are not allowed as a gencral rule to send over the air straight-out messages to individuals. Exceptions are sometimes made, however, as in a case which came under notice this week. A man living away up in the bush came to Sydney to undergo a serious operation. His family are beyond reach of telegraph, and it takes four days for a letter to reach his home. In these circumstances the radio inspector readily agreed to station 2BL, sending "a bulletin" every day as to his progress to his friends in the country.