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The Model Engineer and Practical Electrician. February 13, 1930.*
The "Model Engineer
"1500" Three-Valve Receiving Set.
By H. J. Barton Chapple,
Wh.Sch., B.Sc. (Hons.), A.C.G.I., D.I.C., A.M.I.E.E. IN designing this special three-valve receiver for THE MODEL ENGINEER, I have been guided in my efforts by certain outstanding points. First of all, I learn that this marks the re-entry of this journal into the set constructional field after an interval of many years. Then, again, such a large section of the readers are quite skilled mechanics and delight in taking a pride in their handiwork. With these two points uppermost in my mind I felt that it was not only necessary to present to the readers a set which for performance and appearance would give every satisfaction, but one which would 「 L... MULTI-COIL Y } valves were chosen, for that represents a com- bination capable of giving many alternatives to the local broadcasting programme which can be listened to in comfort on the loud-speaker. To satisfy the bulk of the demands of the potential constructors, such important details as ease of control, simple range changing from high to low wavelengths, the provision of volume and reaction adjustments, high-class reproduction, adequate selectivity for the modern conditions of high-powered stations, good sensitivity and pleasing appearance are all embraced in this receiver. 141 ++ # GRID CONDⓇ AERIAL TERMINAL GRID ELECTRICAL WIRES VARIABLE LEAK CONNECTION CROSSING CONDENSER
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EARTH FIXED CONDENSER FIXED POTENTIOMETER 0000 FIXED wwwww VARIABLE www CELL Low FREQUENCY TRANSFORMER OOHE 3 ELECTRODE VALVE PENTODE VALVE TAPPED LOW FREQUENCY TRANSFORMER RESISTANCES SWITCH OHD FUSE SCREENED GRID VALVE LOUD SPEAKER, DIFFERENTIAL REACTION CONDENSER Fig. 1. Showing Symbols used to indicate Various Components in the "1500" Set. justify completely the decision of your Editor to adopt this course. Important Features. The keynotes for the set were therefore summed up into three salient features, namely, (a) an ability to secure the all-important alternative programmes; (b) musical reproduc- tion of a first-class order; and (c) an ability to reach out to the Continent and satisfy one's curiosity as to what types of transmission are occurring in countries beyond our shores. Once the full details of this MODEL ENGINEER set have been given to readers, I am sure that they will agree that the points mentioned have been fulfilled with a margin to spare. Three The Components Required. All the components have been chosen with care so that they will work together with the greatest efficiency, hence it would be invidious to single out any one item and say the success of the set depends entirely upon the perform- ance of this component. It will be advisable, however, to follow all the working instructions and constructional details with care, for a great deal of time and thought has been spent in laying out the set and reducing the wiring to the shortest possible paths. The complete list of all the components used in the actual receiver photographed and described will be found in tabular form, so that
