Royal Air Force Wireless Experimental Establishment Monthly Technical Report for July 1918

Exp. 636, 654. Wireless Telephony between Machines at High Altitudes using Standard Apparatus. Tests were carried out over different distances and various altitudes to a maximum of 20,100 feet using Bristol Fighters as transmitter and receiver.

Exp. 618. Two Way Telephony. The Trigger Method as shown in Diagram 1062, Fig. I and a variation with amplifier control, see Fig. II. A Method of Coupling a Transmitter and Receiver to the Aerial for two-way working, see Fig. III. Telephonic Code Words. A selection of suitable words for radio transmission is included in the text.

Exp. 647 Alteration to Type 55A to give Wavelengths of 2750 M. Proposed Modifications of Aerial Inductance on Transmitter Telephone Aircraft Mark II. See Diagram Fig. 1059.

Exp. 664. Telephone Transmitter for Fixed Aerials. Using two B valves and the usual circuits as much as 1.7 amperes have been obtained in a dummy aerial equivalent to the standard two-seater fixed aerial, (see report on Exp. 507.) this with nearly 1000 volts on the anode. With the standard 700 volts about 1.4 amperes is usually obtained.

Exp. 654. Tuner Air R.A.F. Type 10. This tuner has an ultimate range of five miles, but ten miles has been obtained from aircraft to aircraft. Illustrations of the tuner are shown in photographs A, (Complete unit), B, (Amplifying Receiver) and C, (Back of Valve Panel of “B”)

Exp. 507. Fixed Aerials Capacitors and Inductances. Capacity and inductance has been tested for fixed aerials installed in Bristol Fighter C 4686 and D.H. 4. No. 6627.

Exp. 603. Cartridge Aerials. A rough breaking strain test indicates that the 12/38 standard wire is 2.3 times as strong as the 7/36 phosphor bronze wire as received from Connolly Bros.

Exp. 521. Intercommunication in Two Seater Machines, especially those fitted with Wireless Telephony. Improved aerial communications using throat microphones due to revised circuitry produced by Capt. Cohen as illustrated in Fig. 1063.

Exp. 617 & 635. Windmill Tests. The Windmill generators A.H. 11B & 12A were tested at various m.p.h. on a D.H.4 aircraft No. 6426 with a 200 h.p. B.H.P engine. The 11B gave satisfactory results.

Exp. 649. Test on Mortley Generator. In the insulation test the armature insulation broke own at 3800 volts D.C. The machine has been returned for repair.

Exp. 665. Experimental Light Weight High Tension Generator, made by Electrical Construction Co. This machine weighs only 8½ lbs. and is smaller and lighter than either the E.T.H. or the Newton machines. See E.C.C. Generator photograph and characteristic curves diagrams 1074 and 1082.

None Tests at Winchester on Generator Disturbance Effect of 6600-volt three phase overhead mains on open circuit. See Diagrams 1064 – 1070.

Exp. 615 & 616. The ‘Negative Resistance’ Properties of B.T.H. (French) and Dynatron Valves. The characteristic current curves are shown in diagrams 1081 (French valve) 1071, 1076, 1078 & 1080, Dynatron Valves.

Exp. 552. Test of Army “B” Valve in T 57 Transmitter at 1200-1500 volts. The “B” valves carry a safer load than the “A” valves at the same voltage and are considered quite satisfactory.

Exp. 662. T. 2 B. Valves and Molybdenum Anodes. The Molybdenum Anode valve does not give any greater efficiency than the standard valve, however it is much safer and will stand approximately three times the dissipation. See curve diagram 1079.

Exp. 666. The “Q” Valve as a Rectifier. The “Q” valve is known to make a very efficient rectifier as illustrated in Fig. 1072, 1077 and 1073.

Exp. 666 Characteristics of “D” valves. The grid curve is shown in Fig. 1075.

Crackling in H.F. Amplifier. Crackling in multi-wave amplifiers is due to the H.F. valves and is not due to atmospherics.

“Q” Valve in Rectifying Position of 7 V. Amplifier. Reduction in crackling was found by replacing the grid leak and rectifying valve with a “Q” valve.

Crackling and Internal Oscillations. With a view of controlling the internal oscillations the rectifying valve was made to oscillate at the natural frequency of its grid transformer.

Direction Finding. The two lines of investigation are: Improvements to the existing system and use of a radio-goniometer with coils fixed on the machine.

Appendix: Weights of W/T Gear in Aircraft. A large proportion of the weight is due to the use of filament batteries which could be replaced with Army unspillable accumulator, type V 03, 6 volts with a weight saving of 20 lbs.