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).
Correspondence querying inconsistent filament current specifications for a rectifying valve used in insulation tests.
| Identifier | ExFiles\Box 41\2\ Scan034 | |
| Date | 16th November 1926 | |
| X3646. To Wd.{Mr Wood/Mr Whitehead} from EFC. EFC4/T16.11.26. RECTIFYING VALVE FOR HIGH TENSION D.C. INSULATION TESTS. Your Wd{Mr Wood/Mr Whitehead}5/NJ15.11.26 to hand, together with attached copy of letter from the G.E.C. The M.R.I. valve quoted would be totally unsuitable for our purpose. As there is no other alternative, we should like you to obtain a definite quotation for the E.H.T. No.2 valve, of which, as they state, full information was given in their letter of the 29th ult. In further reference to the last paragraph of our EFC2/T6.11.26, there must still be some error in the filament current although they say in their letter of the 12th inst. that it is correct at 2.5 amperes. In their previous letter they say, quoting from your copy, "The "The Valve can be run from a 4-volt accumulator, with a small fixed resistance of approximately 1.2 ohms in series; for your purpose the emission at 3.7 volts would be ample. The filament current at this voltage is approximately 2.5 amps." We queried whether this was not intended to be .25 ampere because the passage of .25 amperes through a 1.2 ohm resistance would drop .3 volt, which is exactly the difference between the volts of the accumulator and the 3.7 volts quoted. In fact the figures as given in their paragraph are not consistent. We therefore still do not know whether the filament current really is 2.5 or .25 amperes, and I should like this point to be cleared up. The alternative is that the small fixed resistance [Handwritten correction above '2.5 amperes' reads '.25'] [Handwritten note with caret pointing after 'cleared up' reads 'explanation'] | ||