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WIRELESS TELEGRAPHY 1906© RN Communications Branch Museum/Library |
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WIRELESS TELEGRAPHY 1906© RN Communications Branch Museum/Library |
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| In this file:- | If you have been reading these files as intended i.e., from 1895 onwards, you will have observed a pattern of events and in your mind you might have a mental picture of Captain Jackson and Marconi, the two real powerhouses of the RN roller-coaster, saying, OK, tough, but after 11 years, so far so good. A reasonable assumption don't you think? Well, if you have, your picture needs to be over-painted by the revelations which are about to follow. It starts off slowly but at the finish...well, wait and see!
General summary.
Inter-Fleet W/T exercises - W/T on the up! Four exercises conducted with three major battle Fleets, Atlantic, Channel and Mediterranean and have a quick look at the results of Exercise 3. Here also we come across F Tune for the first time. Connected to the aerial in the old fashioned way (plain) as opposed to 'oscillator', F Tune transmitted on a frequency of 330kHz (3000 >λ) with reception employing the magnetic detector supplied simply to receive Poldhu signals. It was immune from A and B Tune (both on very much higher frequencies) and F Tune employing Tuned Shunts with great success to rid the air waves of as much interference as possible. F Tune was a great success, and the ships using A and B Tunes got themselves into a pickle. Had the exercises revealed an inherent weakness in Marconi's A and B Tunes which could bring about their demise.? What follows is the HARD HITTING report of those manoeuvres. Lets us have a look.
Report by representatives of Channel, Mediterranean and Atlantic Fleets on board HMS Exmouth at Lagos.
Outcome of the meeting which was attended by five Lieutenants Torpedo Branch and one Commander RN, a group which would change the modus operandi for the naval W/T branch recommending such detailed and profound changes which lead to an Admiralty re-think which must have impacted upon HMS Vernon and HMS Defiance, as well of course upon the Marconi Company.
I recommend here that you read the file over to the right. I am simply going to summarise the 14 points which were to alter the navy and in effect, cause a watershed and a change of direction for equipment and operators. The end result would still be the spark-gap age but that wouldn't last much longer anyway as you will see.
They recommended the following changes:
1. To get rid of A Tune (2.5MHz short wave) both oscillator and receiver box.
2. To get rid of B Tune receiver box, and to keep B Tune (950kHz) transmission for peacetime use only.
3. Introduce a considerable number of other Tunes for wartime use which should be kept confidential.
4. To keep the magnetic detector which could receive both B Tune and Poldhu (and other Tunes yet to come).
5. Abolish the coherers.
6. Abolish 'double reception' where an operator would keep his eye on both receivers, A and B just in case he was called on either.
7. For the first time make the operator concentrate on his duties by introducing 'Telephonic Reception', which means wearing earphones and listening to the signals rather than watching them on an ink-marker. Telephonics to become the standard reception method in the Fleets.
8. Could the aerials be combined into one to serve for all purposes - send and receive on all the TUNES and still receive Poldhu out to 2000 miles? Yes was the answer by rigging a special roof aerial which all ships with slight modifications would adopt.
9. Could transmitter circuits be improved to effect quick change-overs to new Tunes? Yes was the answer.
10. How many Tunes clear of each other out to 2 miles (not causing interference to each other) could we have? Answer - Experiments will have to be conducted but we are certain it is at least six providing the Tuned Shunts are used to stop interference.
11. Will AC alternators give better results than DC? Yes, certainly. Inductive coils work at their maximum power with AC, plus, if the enemy jammed a Tune, with an alternator it is still possible to transmit with a distinct note which friendly forces can still read. The alternator would do away with our biggest bugbear which is the hammer make-break on the very induction coil itself.
12. If smoke from the funnel (previously reported) causes so many problems, why don't we move the position of the W/T office? Is the after Shelter Deck a suitable place? They agreed to think about new ships and where the W/T office should be sited, but for the present, to leave the one and only W/T office where it was, and if the enemy were sighted and engaged, the W/T office would be struck and taken below into the armour belt for safe keeping: it was not required when the shooting started.
13. What about the operators? Permanent W/T operators are a must and they are needed now. Signalmen consider it a punishment to have to go to the W/T office to keep watches because they cannot distinguish themselves on the bridge for promotion. There are too few operators in the Fleets. The present state is most unsatisfactory. Training boys from scratch is too lengthy a process - we need operators now. Any member of any branch can volunteer to join the new branch of telegraphists. A good education in reading and writing is required - good character and intelligence - good ear for telephonic reception and an aptitude for reading the magnetic detector after a course of instructions. Branch structure for advancement and promotion, Branch to be under control of the Torpedo Department and Torpedo Officers. An officer from the Torpedo Branch should be appointed a W/T expert and appointed to each Fleet. He should be a Lieutenant Torpedo with sea experience.
14. Bearing in mind that everybody knows our radio callsigns, would it not be advisable to have a definite plan for changing these in wartime ? Yes.
End of Report and Recommendations.
The Tuned Shunts are taken seriously - 90 sets to be issued to the Fleets, and the AC revolution has started with 6 rotaries (alternators) issued for trials.
W/T during grand manoeuvres on July 1906.
S Tune issued as the standard Tune for the RED FLEET and no serious interference experienced from the BLUE FLEET or from ashore. Mediterranean Fleet definite spark note both strong and deep: Channel Fleet high pitched spark note.
Defects and Suggested Improvements -
Existing W/T offices should be shifted to upper deck and all ships should have a silent cabinet. Improved deck-insulators and better insulation. More operators required per ship - two only at present.
Summary of General Policy -
Most powerful transmitters possible to be fitted to increase present range and to render communications more reliable in atmospheric conditions.
Minimum height of masts to be 170 feet.
Destroyers should have a special >λ so as not to interfere with the main W/T communications of the Fleet(s). They should be able to receive all > λ's. All ships will have silent cabinets.
Alternators to be introduced.
Quarterly W/T exercises to be arranged.
Constant > λ changing exercises should be carried out.
W/T experts to Reserve Fleets as well as to seagoing Fleets.
Institution of operators branch as soon as practicable. Minimum number in each ship to be four.
Large power (C Tune) to be fitted in following ships.
C Tune MkII (medium power) to be fitted into following ships.
All other ships will have MkI C Tune (low power).
39 destroyers to be fitted with W/T, both River and Ocean-going classes.
HF Power/alternator advantages.
C Tune MKII/SERVICE MK II - the W/T office will be on the upper deck or the shelter deck.
Many warnings about the danger of electric shock from aerials. Read image below. |
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| In this file:- | In the previous file you will have read the recommendations from Three Fleets on W/T matters. Here we will see the matter of W/T Operators discussed in FULL and in every DETAIL by the Admiralty. What follows is of very special interest to naval boys and particularly to ex HMS Impregnable boys, based on Devonport (same as the Torpedo School HMS Defiance), although it would have been nice to consider my alma mater HMS Ganges where W/T boys joined straight from school at age 15? in my time (1953), but before that, from the earliest of times. (See this file 1907 for details)
W/T Operators - Entry and Training of W/T operators into the Royal Navy.
Operators will be entered as boys and this will be an Average Telegraphists Career. Boys between the ages of 15? and 16? will join their training ship - HMS Impregnable - as follows.
 
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| In this file:- | HMS Vernon's proposed organisation of Wave Lengths (Tunes) for W/T Communications. War communications - personnel shortages with signalmen being singled out. Much practice was needed in the Fleets. Every ship in the Fleet and all shore stations are now fitted with W/T capable of transmitting on five Tunes namely 'Q' 'R' 'S' 'T' and 'U', each one not interfering with the other at a distance of two miles. This system of W/T apparatus is called the SERVICE INSTALLATION Mk1. Typical distances are 'Q' 200 miles day/400 miles at night - 'U' 70/120 miles by night. However, 'Q' is much used by commerce so it is the least selective of all Tunes. Ranges are between battleships and heavy cruisers where heights of 175' above the waterline are achieved. Tune 'C' will transmit of 'S' 'T' and 'U' but its range will be greater than that achieved with SERVICE MK1. The following ships and shore stations will be fitted with 'C' Tune. All ships and shore stations can now receive all Tunes plus of course Poldhu. Procedure for using Tunes. Organisation of wave lengths. All HM Ships should guard (keep watch on) 'S' Tune. 'P' Tune is being reserved for destroyers and 'U' for communications between battle squadrons and destroyers. Short distance signalling and Harbour Exercises. Short distance W/T on the Mediterranean Station. | ||
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| In this file:- | Instruments in general use. New deck insulator to replace the Bradfield device. Aerials to be earthed in thunderstorms. New spark gap silencer. Rotary (AC) converter fitted. New telephone headgear introduced. Scout Class ships to get same receiving gear as large ships. Magnetic detectors issued to destroyers. Leyden Jars (spark gap gear) to be repaired onboard using Flour, Boiling Water, Gum Arabic and a Clove (for preservation). Aerials secured too rigidly - suggestion of weights to avoid stress. Spark details using 1?kW alternator - AC. New 'silent cabinets' (operators cabin) for some ships - what is included in the new cabinet. General arrangements for positions of W/T Offices. 'C' Tune spark gaps. A new magnetic key for 'C' Tune Mk11. Plate VI on pages 16/17 of this file show the new fangled Send/Receive switch for the 'C' Tune. The Bowden wire is rather like that found on a bicycle brake or gear change cable. It looks complicated and a simple explanation will not go amiss - indeed, it might help. The switch (page 16) is fitted in the Safety Cage (nasty transmitter, so no one can touch it or be harmed by it). The hand lever and foot switch (page 17) are fitted in the Silent Cabinet where the operator sits safe from danger. Both pages (16/17) show the send/receive switch apparatus in the RECEIVING MODE. Look first at page 16 at the switch proper. Where it says "sending terminal" (top) and "receiving terminal" (bottom), both of these are connected on the ends of FIXED non-moving arms. Where it says "aerial terminal" (bottom) this is on the end of a MOVING arm which can be put to the receive position (bottom) as shown or to the transmit position (top). Notice that as shown, the MOVING arm's two gold-coloured contacts laying in a NNW-SSE position are not touching the two contacts each shown as four small rectangles (two pink and two gold) inside a larger rectangle. Now scroll to page 17 to the hand lever and foot switch. Note that the hand lever is in the down or bottom position and that the operator is missing from the 'silent cabinet' so there is no pressure on the foot pedal. As stated, the system is set to Receive. Now let us TRANSMIT. The operator lifts the hand lever to its uppermost position and when there he puts his foot on the foot pedal and maintains a downward pressure, which, via the Bowden wire, adds a catch below the hand lever so that it cannot return to the bottom position. He must keep that pressure on throughout the transmission. Back to page 16. The lifting of the hand lever has pulled the Bowden wire down pulling with it the moving arm of the switch. The moving arm leaves the receiving terminal and travels upwards to meet the transmitting terminal. At the same time, the two gold coloured contacts attached to the moving arm move clockwise to engage with the pink coloured contacts of the Spark Gap AC Alternator ending up in a NNE-SSW position. This connects the spark to the moving arm and thus to the aerial. As soon as the message has been sent, the operator takes his foot off the pedal, the lever catch dis-engages, the hand lever drops back down to its bottom position, the moving arms drops, the gold coloured contacts assume the NNW-SSE position and the spark AC alternator is dis-engaged from the aerial and the whole thing returns back to the receive mode. Simple ? Yes! General arrangements of W/T office for the 'C' Tune Mk11 apparatus. | ||
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| In this file:- | Tuning a 'C Tune Mk11. Experiments with HMS Furious - Atlantic Fleet - Directional W/T....Stern towards UK, UK receives loud and clear ship receives little....bows towards UK ship receives loud and clear UK very little - new main roof ?. C Tune Mk11 Diagram of W/T Office and Silent Cabinet. Experiments using various metals for spark gaps. Effect of atmospheric conditions on transmitting distance in W/T - Effects of moisture in the atmosphere on W/T signalling. National Electric Signal Company W/T Station at Machrihanish, Mull of Cantyre (note, not Kintyre) - Fessenden system with range of 3000 miles at night (to near New York) but nothing during the day. 25kW alternator and transformer in oil tank transforming from 1000V to 25000V. Speed 15 to 20 wpm BUT IN AMERICAN MORSE and not international Morse - see file Click Here in this series. The Poulsen System - the first hint of an Arc transmitter ? Morse code achieved by causing the key to connect and then dis-connect the aerial. Transmitter and receiver technology looks very promising ! Berlin conference 1906 - to lay down rules regarding wave lengths, shore stations for commercial purposes etc - all nations agreed and the outcome will become law in 1908. Report of W/T in HMS Defiance. 'B' and 'C' Tunes - Tuners Poldhu - from one magnetic detector 20 pairs of telephonics can be used. Qualifying Torpedo Instructors are examined in reading the Poldhu signals but only 20% get full marks. Buzzer circuit - for training Morse code operators - 10 isolated stations can be used. Graph of volts and spark lengths for spark balls of various sizes. Experiments carried out onboard HMS Defiance. HMS Defiance experiments with W/T in destroyers | ||
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| In this file:- | List of permanent stores for W/T. Aerial condenser curves. Report - long distance trials HMS Vernon to HMS Furious. Signal strength, geographical areas, distances achieved. 'R' Tune = 2500' = 380 kHz good but 7000' = 150kHz very poor. Alternators - remember 230V 50Hz ? Well what about 400 Hz ? - musical spark notes for reading through jamming and atmospherics were well received, and although HMS Culver (6 miles from HMS Vernon) tried to jam HMS Furious' signals from the Mediterranean HMS Vernon could read through the jamming because of the 'high note' produced by the Furious' AC alternator spark. A new alternator with even higher frequencies has been placed on order. Silent Cabinets can get rid of any ship-type noises rendering even the weakest signal readable in the ship. Tune Shunts. Now accepted as amplifying the wanted signal as well as attenuating the unwanted signal. What we might call a band-pass/band-stop filter. Aerial - top gallant mast and W/T yards - coped with the most atrocious weather during the trials. This was because the outhauls were tensioned by weights and not physically secured as taut aerials. In short they were in harmony with the stresses of the rolling, pitching and tossing of the ship. Very early foreign commercial radio callsigns Callsigns | ||