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).
Product specification sheet for an Adjustable Tuning Unit, Type TF456.
| Identifier | ExFiles\Box 138\1\ scan0307 | |
| Date | 1st January 1938 | |
| MARCONI-EKCO INSTRUMENTS LTD. ELECTRA HOUSE, VICTORIA EMBANKMENT, LONDON, W.C.2, ENGLAND. JANUARY 1938 Com. D-7 ADJUSTABLE TUNING UNIT Type TF{T. Fisher}456 [Image of the Adjustable Tuning Unit with the following labels] FREQUENCY RANGE 100-250 250-600 600-2000 2000-5000 FINE TUNING SERIES PARALLEL .1 STEPS .01 STEPS .001 STEPS ADJUSTABLE TUNING UNIT 100 C.P.S. - 5000 C.P.S. TYPE TF{T. Fisher}456 No.2344 MARCONI-EKCO INST. LTD. LONDON The instrument consists of a screened tuned circuit adjustable to resonate over a wide range of audio frequencies. DESIGN The circuit comprises four inductances and a decade condenser together with a switch for connecting these components to form either a series or a parallel tuned circuit. FEATURES The inductances take the form of a tapped iron cored coil for the low frequencies and a tapped air cored coil for the high frequencies. These are selected by a switch engraved to indicate the frequency range. The coils are designed to have a satisfactorily low effective resistance at the working frequency. The tuning condenser comprises two decade dials of .01 μF and .001 μF steps. The range is extended by the addition of two 0.1 μF condensers and a continuous variation of capacity is provided by an air dielectric variable condenser of .0015 μF maximum capacity. The condensers are all of a high stability type and the decade steps have mica dielectrics up to 0.099 μF.{Mr Friese} Complete screening is provided by the welded steel case and metal panel, and the screening of the input leads may be made continuous by means of the special three-point screened connector which is fitted. SPECIFICATION OVERLEAF | ||