Laboratory Jottings

Radio Record, Volume IV, Issue 17, 7 November 1930, Page 9

Laboratory Jottings

Blue Spot Receiver "THERE is no doubt that the popularity of the local station receiver is becoming progressively. more popu: lar, and the introduction of ‘another low-priced electric receiver will .be welcomed. This is the Blue Spot local station set, the New Zealand agents for which (Messrs. Scott and Holladay) have supplied us with a receiver for test. In appearance it is decidedly neat. It is self-contained, small, light and portable. In the front are the grille

covering the speaker and -the two con-trols-tuning and reaction. It is well-finished, properly balanced and unique in appearance. At the back are the protruding valves, three in number, rectifying detector and power valve, two sockets for the aerial plugs, earth terminal, plugs for a gramophone pickup, a wave change knob. and a diaphragm adjuster. To safeguard the valves from falling. out or becoming dislodged, they are held in position by spring caps. For local station reception, the set can be regarded as a _ portable. it ean be shifted to any part of the house, or even outside, providing there is a light socket handy, and with a small piece of wire be made to work at excellent strength. We used the set for this purpose and found that it would receive quite well with a piece of insulated wire 10 feet long laid anywhere handy. There was no need to erect a proper aerial, One of the aerial sockets is specially designed for this type of aerial for it is tightly coupled to the aerial circuit and makes use of the slightest impressed signal. The other terminal we found of _little practical use, for although its use resulted in quite loud signals and Sharp tuning, it was nevertheless of /no great value, as selectivity is not required in such a set. The tone of this set is good, all things being considered. It is distinctly in the leading class of this type of set and very enjoyable tone is secured. It uses an adjustable cone speaker of the "Blue Spot" type and this is an undoubted assurance that the quality will be as good as that type of cone is capable of producing. It will handle quite comfortable room strength without rattling, and as a gramophone amplifier it is quite as good as the table model machines. Apart from the qualities.of the instrument as a receiver of the local station, it has quite good qualities as a distance getter and ean provide a considerable amount of enjovment on the silent night. Without much difficulty we were able to receive the four New Zealand "A" stations, 2BLlL, 2FC and 4QG at comfortable speaker _ strength. This test was made quite

early in the evening before the Australian stations had reached maximum strength. At the time of -the test there were many other stations that we did not stop to identify, and anyone interested in reaching for the smaller Australian stations could derive endless fun from the set. The slow motion dial and the smoothly acting reaction makes tuning to these distant stations relatively easy. It is necessary to alter the position of the three-way switch at the back to receive all the stations usually heard. The switch covers three bands, viz., 180-400 metres, 250-650 metres and 700-2000 metres. Although this latter band is of little use in this country, many who wish to listen to the Morse in those: regions will find it of interest