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 instrument, detailing its construction and operating principles.
| Identifier | WestWitteringFiles\F\January1921\ Scan6 | |
| Date | 7th January 1921 | |
| To R.{Sir Henry Royce} from EFC. c. to CJ. c. to E.{Mr Elliott - Chief Engineer} c. to By.{R.W. Bailey - Chief Engineer} c. to EP.{G. Eric Platford - Chief Quality Engineer} c. to Ba. c. to PN.{Mr Northey} c. to EWT. for R.R. Inc. ORIGINAL. EFC1/T7.1.21. X.4294 - "RADAMAX" PLUG TESTER. We recently received from Messrs. Smith & Sons an instrument called the "Radamax" Plug Tester. This consists of a cylindrical barrel of ebonite with a pair of projecting brass pins at one end, and a small mica window at the other end, behind which is a small spark gap, the sparking at which is viewed through the window. The instrument is held with its terminals one in connection with a sparking plug terminal and one in connection with the base of the sparking plug, and is supposed to distinguish between good and faulty plugs by sparking or not sparking at the sight hole. The internal connections consist of an inductance in series with a condenser and the spark gap opposite the sight hole is connected in parallel across the inductance. The instrument is essentially a detector of high frequency high potential oscillatory voltage, for such a voltage applied to its terminals will readily take effect across the condenser and produce a spark at the gap, in spite of the inductive path across the gap. If the potential applied be not rapidly alternating, no spark would be produced. If the applied potential, though rapidly alternating, be of lesser amplitude, the spark produced will be weaker Cont'd | ||