Abstract
A DESCRIPTION is given in the of December 27 of experiments on the suppression of radio interference produced by trolley buses, carried out by Post Office engineers in several towns. At Southend, ‘stopper’ coils were fitted by the Corporation to its trolley buses. In most parts of the town the suppression of the interference was most satisfactory, but in a few parts of the town it had little effect. This was particularly noticeable in a narrow road in which the trolley bus track turned sharply at each end. Experiments with condensers fitted to the trolley poles were fairly successful in diminishing the disturbance in the troubled regions. Most of the interference was found to be due to the internal electrical equipment of the buses, and tests are being made by electric ‘filters’ to try to improve reception conditions. The weight of the stopper coils when placed on the top of the vehicles lowers the factor of safety for overturning tests and is therefore disadvantageous. Further tests on these coils has been postponed until the development of a lighter coil made of aluminium has been developed by the engineering department of the Post Office. In tests made recently on a G.E.C. Ley land trolley bus at Birmingham, good results were obtained by the application of interference filters to the individual items of the trolley bus equipment, and similar tests were carried out on one of the Hastings trolley buses. The items of the equipment causing interference were the controller, driving motor (60 horse-power) and collectors of the wheel type. Experiments showed that good suppression can be obtained by using these filters, but possibly line condensers will also be necessary. The tests show how serious the interference sometimes is when the weather conditions are bad, and that much of it can be suppressed by ‘stopper’ coils.
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Suppression of Radio Interference. Nature 137, 60 (1936). https://doi.org/10.1038/137060b0
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DOI: https://doi.org/10.1038/137060b0