Laboratory Jottings

Radio Record, Volume V, Issue 18, 13 November 1931, Page 6

Laboratory Jottings

Radion Sxe WE have received from Messrs. H. W. Clarke and Co. a Radion Midget seven-valve receiver, which has been manufactured in New Zealand. The set-one of the super-heterodyne type-employs two multi-mu and two screen-grid valves, a 227, a pentode, and a 280 rectifier. The appearance of the set compares indeed favourably with modern set design, and it reflects great credit upon the designers. It is equipped with three controls-tun-ing, tone and volume-switch-the dial being of the recessed, conical type, with graduations marked in degrees. The chassis is particularly well made, only the highest grade of com ponents being employed, and we would: mention in passing some of the com, ponents we noticed. The condensers are Standard and T.C.%., the variable condensers de Jur, the valves Sylvania, while the transformers, chokes and coils are locally made. The use of high grade components such as these can only result in a first-class production, and this the manufacturers have achieved. . On a sensitivity test the set proved equal to a standard seven-valve superheterodyne receiver, Australian’ and Japanese, including many of the minor stations, being received on a standard aerial. On a short piece of wire the set proved .itself capable of bringing in the main New. Zealand and Australian stations without difficulty. In the selectivity test, the set, worked with a 100ft. aerial some five miles from 2YA, was asked to separate 2YA in favour of 2FC and 4QG. This it did without a trace of interference. 2YA was restricted to a very narrow band indeed. In the fidelity test we listened for reproduction both ends of the scale, with the tone control in a minimum position. The extremes were there all right. The tone control eliminated the higher frequencies, so that any grade of tone could be obtained. The pentode has a very characteristic tone, possessing as it does a rare brilliance of upper notes. The volume control, although operated in its minimum position on local stations, does not introduce distortion, being smooth and regular in operation.