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).
The 'Radamax' plug tester, explaining its function and requesting a trial on experimental cars.
| Identifier | ExFiles\Box 50\2\ Scan008 | |
| Date | 7th December 1920 | |
| To Hs {Lord Ernest Hives - Chair} /TMW. from EFC. {E. Fowler Clarke - Electrical Engineer} X.4294 EFCl/T7.12.20. X.4294 - "RADAMAX" PLUG TESTER. We are handing you herewith a Radamax plug tester for trial. This is my own property, having been given to me by Messrs. Smith. It is supposed to distinguish between good and faulty plugs by sparking or not sparking at the sight hole when connected across a good or faulty plug respectively. The principle upon which it works is that between its terminals there are connected in series an inductance and a condenser, and across the terminals of the inductance is placed a short spark gap at the sight hole. If the sparking plug across which it is placed is good, the high frequency oscillatory initial spark discharge exists and this sets up in the instrument a discharge through the condenser and across the spark gap, the discharge being unable to take place through the induttance and so missing the gap, owing to its high frequency. Thus a spark is caused at the sight hole at the same time as the initial oscillatory spark occurs at the plug. If, on the o-ther hand, a plug be foul, the discharge in leaking away or occurring at a lower voltage will not allow the high frequency discharge to take place so readily and therefore no spark will be produced at the sight hole. Will you kindly have this tried on the experimental cars and let me have a report upon the result at your convenience. I can spare the instrument for a week or two for the purpose. EFC. {E. Fowler Clarke - Electrical Engineer} | ||