From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Tests for wireless interference on a 20/25 HP engine fitted to a light tank.
| Identifier | ExFiles\Box 163\2\ img037 | |
| Date | 31th January 1933 | |
| COPY. WIRELESS INTERFERENCE ON 20/25 HP. ENGINE FITTED TO LIGHT TANK. The War Office representatives have now carried out tests in conjunction with ourselves on the light tank at the Works fitted with a 20/25 HP. engine rigged up with ignition screening as originally proposed by the D.O. The tank was taken out to a spot near the Works where as little outside interference as possible could be heard. The engine was then run light and tests made with a wireless receiving set for interference. It was found that with the L.T. filter unit in circuit between the ballast resistance and the ignition coil all L.T. interference was eliminated. This filter unit consisted of a choke and condenser sent to us by the War Office to which we added another similar choke at their request in order to double the filter circuit inductance. A slight buzz, however, was still audible on short wave receptions and this was thought to be due to H.T. disturbance. The dynamo gave no interference at all, without any chokes or condensers interposed on the wires to the battery. Upon running the tank pulling under load, the H.T. interference, although only slight, became more pronounced, this being due to the extra load put on the engine raising the voltage on the spark plugs. This interference, however, could only be heard on the short wave lengths. The War Office representative stated that he thought the H.T. interference with the tank in motion was a little too pronounced. He thought that perhaps the mere screening of the plugs would cure all disturbance. He is submitting a report to his superior officer at Woolwich and as a result of his report we may expect to hear further from them. Although Mr. Archer and myself considered the interference to be negligible, the two War Office representatives thought that on the short wave lengths the interference might cause indistinct telephonic reception. Our own opinion is that the screening on the tank is reasonably O.K. from a wireless interference point of view. | ||