Under the Shadow of a Powerful Station

Radio Record, Volume II, Issue 51, 5 July 1929, Page 27

Under the Shadow of a Powerful Station

How a Receiver is Best Operated

. AS listeners are aware, a new powerful 2LO, London, has been erected and in writing to the "Morning Post," W. James stresses valuable points concerning the use of a receiver in close proximity to a powerful local station. His advice is repeated in these columns in order that it may strengthen or collect points that have from time to time been given listeners in this respect. "Those who live within a few miles of the new station when it begins transmission will receive a very strong signal, with the result that there will be a tendency for the receiver to be ovetloaded. This will have the effect of spoiling the quality of the reproduction unless the receiver is fitted with an effective volume control. "As only a small number of sets have a volume control, those listeners who experience overloading will have to reduce the size of their aerials, or alternatively, fit an adjustable resistance in the aerial circuit of their receivers or across the cireuit connected to the first valve. A modification of this type will not be very expensive. "It will prove much more difficult, -however, to cut out the powerful local transmission and to tune in distant stations. Much will depend upon the type of set employed, and if this is a simple one, the user will probably find himself unable to effect inexpensive modifications which will have the desired result. Meeting New Conditions. "' THE effect of reducing the size of the aerial, and of fitting a small condenser in the aerial circuit, may, of course, be tried, but it will probably be necessary to add a further tuned circuit or a high frequency stuze, and it may proye essential to employ a frame aerial. "Those who have a portable receiver may find that by taking advantage of the directional properties of the aerial included in the set, other stations may be received, but it is not possible to say whether all sets of this type will be sufficiently selective. "The points I wish to emphasise are that those who live within a few miles

of the new station will find they are not able to receive other stations so easily as before, but they will have a very strong signal to deal with. Those who are considering the purchase of a receiver, or those who build themselves a new receiver during the summer months-and I find a number of listeners do this-should, therefore, bear. these two points in mind, and make certain of providing adequate selectivity and an effective volume control. Wait and See. "MAN UFACTURERS realise that in the future selectivity will be of even greater importance than in the past, and I believe a number of interesting receivers at low prices will be forthcoming. ‘The all-metal construction which was favoured in certain quarters during the past season may be more greatly employed in the popular sets of the future. "Complete shielding, the use of suitable tuning coils and shielded valves, and the production of fewer types of receivers will be responsible for simplifying tuning and improving the results, New and improved valves also help the manufacturers, and it is expected that large number of sets will be sold during the season. "There is still room for better loudspeaker construction without increasing their cost. Good loudspeakers are relatively expensive as compared with the receiver itself, and the cheaper instruments are not so good as they should be for the sets with which they are used. There are, unfortunately, a number of inexpensive foreign-made loudspeaker units in the country which give very good results. Numbers of amateurs are therefore building their own loudspeakers from sets of parts. "This would not occur were there a supply of good loudspeakers reasonably priced. Unfortunately, sensitivity is often still considered of more importance than quality of reproduction. but when strong signals are more easily obtained than at the moment, the manufacturers will be free to design their products to give the desired quality without bothering so much about sensitivity."