The Inter-war Years: A comparison of British Navy, Army
and Air Force Telecommunications Developments
Anthony C Davies
Emeritus Professor, King’s College London
Introduction
The British Navy realised very early on that radio offered benefits for communications to, from or between
ships compared to waving flags and flashing lights, and using fog-horns during poor visibility.
Control of a worldwide empire also meant a need for long distance communications, making radio attractive –
initially assumed to need long waves.
It must be recalled that for the last half of the 19 th century and up to the start of WW1, there had been great
progress in telegraphy using undersea cables, and so fast communication of text and numerical data by these
means was well established and considered by many to be sufficient, slowing down serious interest in radio
and leaving the first commercial exploitation open to Marconi from the end of the 19 th century onwards, but
with strong interests developing from parts of the British Navy [1].
By contrast, the British Army was expected to be mostly static or slow moving, and typically dug into
trenches or taking part in fixed battle confrontations. The fast-moving German ‘Blitzkrieg’ of WW2 was not
foreseen. Field telephones and motor-cyclists were assumed good for most communications needs so radio
adoption was initially slow, and senior officers are reported as suggesting that radio was to be used only in
special circumstances rather than routinely
For the Air Force, a main use of radio was initially thought of as ‘spotting’ targets for artillery, so the need
was to send messages to artillery on ground. This was simply an extension of the practice of having
observers on high ground to locate enemy targets, the aeroplane simply had the advantage of greater height.
Until the formation of the Royal Air Force in 1918, and the Air Ministry, the Navy and the Army had
unrelated flying entities, the Royal Flying Corps and the Royal Naval Air Service.
The Admiralty made substantial and thorough investigations of radio communications from before the start of
the 20th century. A Signal School for the Royal Navy was formed and carried out many careful experiments,
constructing much of its own test equipment, etc. and producing accurate and meticulous documentation and
drawings. The Signal School developed from within the Torpedo School, which had been established in
1879, at Portsmouth.
Commercial equipment installed on ships was largely associated with the Marconi Company, which tried to
have a monopoly, and around 1912 was the subject of a controversial contract with the UK Government [2].
As a result of rumours of impropriety, a Select Committee of Enquiry was set up in October 1912, and in
evidence to the Committee, Marconi stated …. if the Government had made a contract with any other
company than the Marconi, they would have had to alter the apparatus on all the ships of the British navy,
since these have installations of the Marconi system …. ([2], p161)
Initial military use of radio used Morse Code, typically by means of spark transmission, but with some use of
arc and alternators, and the receivers were at first crystal sets until the first thermionic valves were available.
Naval spark transmitters used high voltages and powerful sparks, leading to substantial danger and need for
care in a ship environment with salt water and bad weather to be encountered. Descriptions include 16kV
and 17A for 18 wpm Morse and, prior to 1900, use of 5 inch sparks to achieve a 17400 foot range!
Spark transmissions produced many kinds of wide-band interference, but they continued in use for some time.
The International Radio Telegraph Convention, Washington DC, 1927 placed requirements on their
termination. There were to be no new spark transmitting installations in Land or Fixed stations from 1930,
shore stations were forbidden from using ‘damped waves’ from 1935. No new installations were to be in
ships or aircraft from 1930 – unless below 300W, and all spark transmissions were to be forbidden from 1940
except for ship standby and emergency use. Thus the phasing out of spark transmissions was a very slow
process.
Reminder of Terminology
Telegraphy is used to refer to “data transmission” (e.g. Morse or Teleprinter, etc.) and Telephony is used for
speech (or music) – initially dismissed as ‘frivolous, with no serious applications’.
The terms W/T for Wireless Telegraphy (e.g. Morse Code, etc.) and R/T for Radio Telephony (e.g. speech)
were adopted and invariably used in military literature and speech.
CW is for Continuous Wave (the carrier keyed on an off by a Morse Key). The receiver requires a beat
frequency oscillator (BFO) to make the Morse audible. The operator of the receiver can then adjust the pitch
by variation of the BFO tuning, which has advantages for listing to one transmission in the presence of
interference from others on slightly differing frequencies. MCW is for Modulated Continuous Wave (the
carrier is not interrupted, modulation at an audio frequency is keyed on and off by Morse Key). Here, the
transmitter determines the pitch.
Hand Morse is commonly at around 20 wpm. Automatic senders and
receivers were developed for very high speed Morse code (400 wpm or more)
ICW, for Interrupted Carrier wave (various forms), is a term not now used but was in common Navy use,
usually referring to a train of damped oscillations keyed on and off in accordance with the Morse code.
The Creed-teleprinter code used five hole paper tape (e.g. five binary characters per code letter).
World War One equipment legacy
Figs. 1 and 2 show typical items of battlefield equipment of WW1. A 1917 spark transmitter, “loop set”, for
65 metres, made at the War Department factory in Soho (Kurrajong Radio Museum Collection), and a 1915
crystal receiver (Duxford Radio Society Collection). For mobile use, heavy ‘wagon‘ and ‘lorry’ sets were
developed.
Fig.1 W/T set Forward Spark 20W B (Rear
Transmitter)
Fig.2
Army Crystal Receiver (1915)
Technology Progress in the Inter-war period
While the details might be open to debate, it can be concluded that during the inter-war period there was very
rapid and substantial technology advance in Radio and Electronics, but this was driven by ‘commercial
capitalism’ (many small and often new companies, aiming to benefit from radio, television, etc. – and a few
big companies making and using scientific advances – e.g. in thermionic valves) rather than by military
initiatives and perceived needs.
Because of WW1, and a hope that it was ‘the war to end all wars’ there was widespread ‘anti-war’ and pacifist
sentiment in Britain and as a result, military spending and development on radio and related topics was
limited, although this appears to have been modified by the needs to maintain an Empire which needed
military strength and local operations to prevent rebellions etc. Plans for the ‘Imperial Chain’ wireless
communication system operating on long waves were made but not significantly implemented, and in effect
‘overtaken’ by the discovery that short-waves and directional antennas provided a better method.
Until about 1930, almost all British Navy usage was long waves. The B11 of 1930 was one of the first short
wave Navy transmitters (Fig. 3). Notice the Navy practice of almost always having the circuit diagram
inscribed on a front panel of their radio equipment. The Navy adopted the Marconi CR 100 receiver (calling
it the B28, Fig. 4) because their own designs were cumbersome to use with multiple tuning dials, etc. (Photos
from the HMS Collingwood collection)
Fig.3
Navy B11 Transmitter
Fig. 4
Navy B28 Receiver
Fig. 5 shows a Canadian Marconi Co transmitter of this era for CW and MCW, with a power output of about
150W. The MCW can be set to 500, 700 or 1000 Hz, and operation is on only on three frequencies in the
range 260kHz to 520kHz. The complete set used only four valves (Two RVC-10 and two RVC-211, all
triodes). RVC stands for Radio Valve Company of Canada, formed in 1922. RVC-211 is equivalent to VT4C [4]
Fig. 6 shows a typical antenna system of a Tanker of this time.
Fig.5 Naval W/T transmitter ([3], p374)
Fig.6
Merchant Navy Tanker antennas ([3], Fig.16-8)
Many Army sets were planned and developed during these interwar years. Investigations and developments
in designing and making transmitters and receivers were extensive (see Muelstee [5,6]) – but the many
designs were often impractical for mass production, and a number of them were never carried through to
actual use. Army designs were mostly handled by the Signals Experimental Establishment (SEE) at
Woolwich. This had its origins in the Royal Engineers around 1903, and after the 1930s, became SRDE and
moved to Christchurch in 1943.
The first plans for having wireless communications to and from tanks were begun just after WW1, and these
culminated in the WS 19 tank set, which came into use from 1941. It comprised three parts, the main ‘A’ set,
which was an HF transmitter-receiver providing CW, MCW and R/T in the range 2-8MHz, the ‘B’ set which
was a single CV6 valve transmitter-receiver using super-regenerative reception in the range 229-241 MHz for
local communications between nearby tanks using R/T (shown in the right hand side of Fig. 14), and the
‘C’ set which was a simple intercom amplifier for use within the tank.
During the 1920s and 1930s, there was a huge increase in popularity of radio, the start of TV, radio valve
progress was very rapid and many small radio-manufacturing companies existed in Britain. Radio valve
developments required the resources of large companies with scientifically based staff and equipment, leading
to many improvements. The EF50 development by Philips for TV was very useful later for military
applications, and manufacture was brought to Britain in 1939 just before the German invasion of the
Netherlands [7]. It led the way in all-glass valve construction.
At first the Navy, Army and Air Force had their own numbered series of valves, for example, ATP4 was the
designation of ‘Army Transmitting Pentode, number 4’, but later the Common Valve Department (CVD) was
set up to unify the ranges using the CV numbering system, and, for example, ATP4 became CV1366 [8].
The ‘transceiver (Sender-mixer) principle’ which ensures that a transmitter-receiver set can be assured of
transmitting on exactly the same frequency that it is receiving, was adopted by the Army, probably starting
with WS 11. In a network, one station is designated the ‘master’ and sends an unmodulated tuning signal.
The others tune in to this using a BFO, adjusting for ‘zero beat’. The BFO frequency mixed with the local
oscillator frequency makes the correct frequency to drive the transmitter.
By 1917, communications between flying aircraft was becoming of interest, and since, particularly in a singleseater plane, operating a Morse key and flying the plane was rather difficult, there was immediately an interest
in using speech.
By the 1930s, transmitters and receivers were being fitted to most RAF bombers. The T1083 (Fig.7) provided
CW and ICW on all bands , which included 136-500 kHz). R/T was possible on only three h.f. bands (3-15
MHz). The corresponding R1082 (Fig.8) is a 5-valve TRF receiver, using plug-in coils for band-selection.
They were replaced in WW2 by the well-known T1154 and R1155. Most versions of T1154 covered 200500kHz, and 2.35-16.7 MHz in four bands, and most versions of the R1155 covered 75-500 kHz (in 2 bands),
600-1500 kHz, 3.0-18.5 MHz (in two bands). The Plessey TR9 transmitter-receiver was installed in fighters
from 1930, operating on 5MHz, using R/T between aircraft and between ground and aircraft.
Fig.7 Transmitter T1083 for bomber aircraft (1930s)
Fig.8
Receiver R1082 (1930s)
For British Army radios [9], WW2 commenced with mainly amplitude modulation in HF (1-10 MHz) range.
Successful battlefield radios by early years of WW2 were the WS 8 which led on to the WS 18 and the WS 9
(and other vehicle designs) which led on to the WS 19. Since the WS 18 was carried on the back, it required
either two people to carry and tune, or else had to be taken off to make adjustments: the operator cannot
adjust settings or frequency while carrying the set.
A single person portability requirement (carry AND operate) led to the WS 38.
The photo of the WS 38 Mark 2 (Fig.9) shows the primitive tuning arrangement: tightening the dial in position
could have the effect of moving it off-tune, and in any case, the frequency was subject to drift with
temperature and battery voltage changes.
Fig.9
Tuning dial of WS 38 Mark 2
Fig.10
R103, Mark II receiver, 17 – 75 MHz
The radios were mostly heavy, with an army belief that they had to be robust to prevent damage (overlooking
the probability that a light-weight radio might be less likely to be dropped or mishandled), they had high
power consumption in relation to their output powers and there was a need to ’hide’ antennas, since these
could provide good target indicators for enemy snipers. Only limited movement was possible.
Fig. 10 is an Army communications receiver of the pre-WW2 time: it is notable that the construction style
makes it look like something which could have been built by an amateur in his garden shed! The more
professional appearance of the R107 which replaced it is shown in Fig. 11, alongside the corresponding WS
12 Sender (Fig. 12), the output of which was from one 807 beam tetrode (ATS25), providing 25 W on CW
and 7W on R/T. A high-power add-on (RF Amplifier No.1) was developed in 1942, using two ATP100s
(CV1372), which took the output RF from a standard WS 12 and increased it to 350 W for CW and 250 W for
R/T.
Fig.11
R107 Receiver, 12–175 MHz
Fig.12
WS 12 Sender, 12–175 MHz
Fig.13 shows the external construction style of the WS 11 (photo from eBay) and Fig.14 shows the internal
construction of the WS 19
Fig.13
Front panel of WS 11
Fig.14
Inside the WS 19
The importance of wavemeters [10, 11]
Until the relatively recent development of accurate crystal control and digital frequency synthesisers,
wavemeters were important for setting transmitters and receivers to the required frequencies and for deciding
the frequency of incoming signals. Navy, Army and Air Force each developed their own wavemeters with
only a few examples of cooperation and sharing. Navy wavemeters were typically incorporated in the
transmitter and receiver structure within the wireless office on a ship. The Army used some wavemeters in
WW1, including some derived from Admiralty designs. The Army Class D no. 1 wavemeter was a simple
heterodyne type introduced early in WW2, and the USA BC-221 seems to have met many other Army needs.
By contrast the Royal Air Force developed many wavemeters, with very different requirements for those to be
used on the ground and those to be used in the air. Fig.15 shows an early heterodyne wavemeter, which was
then called a ‘syntoniser’, Fig. 16 shows the W37 from 1925, for 500kHz-6MHz, which had a buzzer to
enable it to emit a train of damped oscillations, and Fig.17 shows the W1081, which used a single valve as a
detector, and is mounted on a wooden tripod for measuring in the ranges 135-500 kHz and 3-15 MHz. By the
early years of WW2, the RAF required many different wavemeters including ones for use with navigational
aids such as OBOE and for radar.
The British Army did not follow USA practice of VHF or total Crystal Control or f.m. until after WW2 when
there was significant progress towards much simplified operation and greater internal complexity, together
with a move to VHF and f.m., following USA practice. Key developments of that time were the WS 88 and
WS 31, the latter being closely based on the USA SCR-300 and remaining in British Army use (and by
NATO) for many years. The WS 31 AFV was a version for vehicle use.
Fig.15 Early RAF wavemeter
Fig.16 RAF W37 wavemeter
Fig.17 RAF W1081 wavemeter
Fig. 18 shows the simplification in operation brought about by progress and change in technology, and Fig. 19
shows the associated increase in circuit complexity.
WS 18: Sender (Receiver is same size,
WS 88: send-receive switching is by a
positioned above)
press-lever on a hand-held cable
Fig.18 Reduced operation-complexity
WS 38 Circuit Diagram
WS 31 AFV Circuit Diagram [12]
Fig.19 Increased Circuit Complexity (and change to all-glass miniature valves)
Acknowledgements
John Blaney, former curator of the REME museum when at Arborfield, Ron Denton of Duxford Radio
Society, Bill Clegg, former curator of the HMS Collingwood collection and staff of the RAF museums at
Hendon and Henlow are thanked for information and permission to take photographs during various visits.
Figs 3,4,7,8 are all from the Collingwood collection.
This paper is a more detailed version of a paper presented at a conference on ‘Telecommunications in the
Aftermath of World War 1: Civilian and Military Perspectives’ at the IET, Savoy Place, London, on 10th
August 2016.
References
[1] K. G. Beauchamp ‘History of Telegraphy’, IEE, 2001
[2] F. Donaldson ‘The Marconi Scandal’, 2013, Bloomsbury Reader, London
[3] H.M. Dowsett and L.E.Q. Walker ‘Technical Instructions for Marine Radio Officers’ Iliffe, 9 th edition, 1950
[4] http://www.jproc.ca/f/ltt4.html accessed 2016/08/20 (details of LTT-4 transmitter)
[5] L. Meulstee ‘Wireless for the Warrior’, Compendium 1, 2009, Emaus, Groenlo, Netherlands
[6] L. Muelstee ‘Wireless for the Warrior’, Volumes One and Two, 1995, Wimborne Publishing, Dorset, England.
[7] R.Dekker, ‘The EF50, the Tube that helped to Win the War’: http://www.dos4ever.com/EF50/EF50.html
[8] R.S.G.B. ‘Service Valve Equivalents’ January 1947, London
[9] A.C. Davies, ‘WW2 British Army Battlefield Wireless Communications Equipment’, HISTELCON, Paris,
September 2008, pp 83-90, IEEE Cat. CFP08HIE-CDR,
[10] A.C. Davies, ‘Wavemeters for Frequency Measurement by the British Army in World War Two’, AWA (Antique
Wireless Association) Review 2012, Vol 25, pp79-101.
[11] A.C. Davies, ‘The Rise and Fall of the Military Wavemeter: British Military Wavemeters of the 20th Century’,
HISTELCON 2012, Pavia, Italy, 5-7 September 2012.
[12] VMARS manuals: http://www.vmarsmanuals.co.uk/archive/files_index.htm