Exp. 530 Magneto Noise Elimination This experiment combined with……

Exp. 531 Instructional Sets on Boards. Cancelled in accordance with minutes of last conference.

Exp. 507, 654 Built in Fixed Aerials. Aerials, of the same design as those fitted outside the planes have now been built inside the fabric. In preliminary tests on a Tuner, Air, R.A.F., No.10 the results were not quite as good as with the external aerials.

Exp. 510.

Oxygen Gas Mask Microphone. Transmission tests were carried out with capsules No. 4 – No. 11 fitted in the Gas Mask Attachment.

Exp. 521 Intercommunication T/ny on Aeroplanes Report on Intercommunication Between Pilot and Observer in Two-Seater Aeroplanes. See Appendix No. 35. Transmitting aircraft D.H. 4, No. A 7689 and receiving aircraft Bristol Fighter, C No.6411

Exp. 524 H.F. Amplifier for Telephony. This apparatus superseded by later models.

Exp. 525 250-watt C.W. Aeroplane Transmitter. Suspended.

Exp. 526A Ground to Air Telephony. (Medium Range) This experiment covers three transmitters, 120 Tonic Train, the Unit H.T. 120-watt Tonic Train and the attachment Telephone 120-watt Tonic Train.

Exp. 526 Ground to Air Telephony. (Long Range) A more satisfactory set designed to replace the Tonic Train units for Telephony purposes. The source of the power is the I.K.W. 2000-volt Newton Generator, used with T2B valves.

Exp. 527 Microphones and Head Receivers. Work in progress but nothing further to report.

Exp. 604 Magneto Noise Elimination (In Handley Page Machine) Attempts were made to wire up the Rolls Royce Engine with all plug leads running close to cylinder and crankcase as proposed by S.E.E. Woolwich but proved impracticable due to the heat. Screening of the magneto distributors is achieved using a bag of copper gauze covered with balloon fabric.

Exp. 605 Listening-Through Key for T.57 Transmitter. Experiments are in progress with a modified form.

Exp. 601 C.W. Transmitter, Type 56c. No progress to report.

Exp. 602 C.W. Syntonizer (Long Wave) for use with 7 – Valve Amplifier. Nothing to report.

Exp. 603 W/T Cartridge Aerials. This is complete except in regard to the possible use of a cheaper type of wire. (See Exp. 632). See appendix 39 and photographs Fig. 1, 2, 3 and 4.

Exp. 606 H.F. Amplification of Short Waves. Experiment concluded and experimental number cancelled.

Exp. 607 Pure C.W. Transmission with A.C. The whole subject is being held in abeyance.

Exp. 608 Direction Finding. Experiments are carried out on a Handley Page machine with the fitting of a standard arrangement of wing and fuselage coils

Exp. 609 The Wave Form of the Anode Current and its Variations with the Amplitudes and Mean Values of the Grid and Anode Voltages and other Numerics of the Circuits. The wave form curves shown in Figs. 1032 to 1036 of the anode current impulse are plotted for certain adjustments of the C.W. Transmitter T56b.

Exp. 615 Investigation of the Negative Resistance Properties of B.T.H. Valves. Nothing to report.

Exp. 616. Investigation of the Properties of the Dynatron Valve. The results of Captain Mullard’s tests have been received and will be reported on later.

Exp. 617 Test of Windmill for Telephone W. Aircraft MK. II on Handley Page. A windmill generator was placed centrally between the near struts from the top plane to the fuselage on a Handley Page C. 3491 aircraft. Voltage reading of 500 to 700 volts were achieved.

Exp. 618 Two-Way Wireless Telephony. New Method of Control. In this new system, the sending oscillations only appear while the sender is speaking, thus the necessity of the “send receive” switch is overcome. See Fig. 1031.

Exp. 619 Tests of Davis Accumulator Finished and Experimental Number cancelled.

Exp. 620 Call up Variometer for Types 56b and 56c. Model has been completed and calibrated and will be submitted to a full load test on a Type 56b Transmitter. Two models are being made for Dunkirk. (See photograph B)

Exps. 621 and 630. Selective Attachment to Tf Receiver for all Ranges. The present design is being modified to operate on C.W. ranges as well as spark. These experiments are now combined under one title.

Exp. 622 Bushing on S.S. Airships fitted with Type 57 Transmitter. Finished and experimental number cancelled.

Exp. 624 Tf Receiver Tested for “Howling”. Finished and experimental number cancelled.

Exp. 625 C.W. Method of Measuring the Self-Capacity of a Coil. Referred to in April Monthly Report, but at that time had not been fully developed. See Fig. A & B in Diagram 1037.

Exp. 626 Method for Standardization of C.W. Syntonisers. Further work is required on the assumption that the harmonics occurring in a valve circuit are exact frequency multiples of the fundamental.

Exp. 627 Transmission with Tf Receiver. Experiment concluded and number cancelled.

Exp. 628 Comparison of Amplifiers at Portsmouth, June 1918. The Signals School 7-valve Amplifier F2 was compared with the Cranwell 7-valve Amplifier on ‘tonic train’ and C.W. for wavelengths from 3000 LS. To 15000 LS.

Exp. 632 Tests of Aerial Wire Experiments on samples of hard and soft copper, 3-strand and 9-strand wire from The London Electric Wire Co. to replace the more expensive 12/32 phosphor bronze wire used in Cartridge Aerials.

Exp. 631 Send-receive Key, New pattern. Completed and number cancelled.

Exp. 633 Diplex Reception for Ground Stations. Concluded and experimental number cancelled.

Exp. 634 7 – Valve Tuner, Short Wave. It has been decided to standardise on 5 -valve Tuner, Air, Typo No. 10 and in consequence the above experiment is cancelled.

Exp. 635 Telephony Between Single-Seater Scouts. In abeyance.

Exp. 637 Slip Stream Air Speed Measurements. Completed and number cancelled.

Exp. 638 Frequency Changer In abeyance.

Exp. 639 Telephones on Kite Balloons. Suspended awaiting developments of 2 – way working for Wireless Telephony (Exp. 618)

Exp. 640 Shed Tests on Transmitter T. 52A, and Type 57. Proposed arrangement of a geared hand drive to rotate the generators rather than applying a low voltage to the exciting circuits.

Exp. 641 Galvanised Iron Wire Ground Mats. Experiments in using ½” mesh galvanized iron wire netting in place of a standard copper equivalent.

Exp. 642 Windmill with Adjustable Pitch. Nothing to report.

Exp. 645 Receiver, C.W. S.W. (Wave-length 50 – 300 metres) Experiment concluded and experimental number cancelled.

Exp. 644 Geared Hand Drives for Generators. This is in hand in the shop. Photograph “C” shows the preliminary model.

Exp. 646 Increase of Wave-Length of No. 1 Transmitter to 350 metres. No alteration to the primary condenser was necessary, an increase of one outside turn on the primary gave an increase in wave-length to 350 metres.

Exp. 647 Alteration of Type 55A Set to be Capable of Transmitting on 2650 metres. This work has not been undertaken but a report has been received from Netheravon upon changes to type 55a made there.

Exp. 648 Conversion of Telephone Wireless Aircraft MK II Set Transmitting (400m.) to Morse Key C.W. (700m.) The object of this alteration is to provide a stop gap C.W. Transmitting Set for High Bombing Squadrons or other purposes transmitting from ground to air for a range of 100 miles.

Exp. 649 Tests on the Mortley Generator. Illustrated in photographs “E” and “F”. This generator is designed to give 1500 volts, 100 milliamps D.C. at a speed of 3600 R.P.M. Air tests are about to be carried out with the generator, and full tables of all tests will be supplied as soon as the necessary instruments are available.

Exp. 650 Substitution of Mains Condenser in Transmitter for that in Generator. A Dubilier condenser of 0.5 mfd. Can be conveniently attached to the transmitter box across the mains and is an efficient substitute for hat in the generator, see Fig. 1042.

Exp. 654 Tuner, Air, R.A.F. No. 10. Fig. 1028 shows diagrammatically the arrangement of the parts of this tuner, and photograph “A” represents the actual instrument. The tuner has been tested in the air on the modified fixed aerial on the Bristol Fighter 4611 and a maximum range of 7 miles was obtained.

Exp. 655 7-Valve Amplifier. The 7-valve amplifier is being designed to suit the V.24 valve which will fit in a panel the same size as that used in the R.A.F. Air Tuner No. 10.

Exp. 656 Electrostatic Voltmeter (2,000 volts) Type K.B.B. Photograph “D”. Comparing with the 1800-volt type K.B.B. the 2000 voltmeter was found more suitable for aircraft purposes.

Exp. 657 Graphite Grid Leaks (Automatic Telephone Co.) Five resistors were tested and again after an interval of four weeks, poor results were found. This type of resistor is not sufficiently constant for service use.

Exp. 658 Valves having Negative Anode Characteristics. This is a three-electrode valve in which the controlling electrode (grid) is not between the filament and the anode, as in other valves, but is placed on the opposite side of the filament to the anode. See Figs. 1029 and 1030.

Exp. 659 Tests of Victoria H.T. Dynamo (done at S.E.E.) This is designed to supply H.T. for continuous wave transmission and telephony from aircraft. The characteristic curves I to III, are shown in Figs. 1038, 1039 and 1040.