In the
environment of a trench it was a trifle uncomfortable when it
came to operating a transmitter. Here an NCO, festooned with cables
is using a medium power trench set precariously balanced on a
packing case covered with a piece of canvas.The mainstay was the runner who braved bullets and shells, mud and mayhem, to take messages to and from forward positions and the rear. Although telephones were relatively commonplace they relied on wires which were easily cut by shellfire or accidental damage. Less common was radio, and this was used both on the ground and in the air especially during the latter stages of the conflict.
A prime use for the telephone was from very vulnerable forward positions acting as observation posts for the artillery positioned some distance away and it was usually not a very happy soldier who was told, in the face of shellfire and rifle bullets, to trace and repair breaks in the wire.
It was not uncommon for a battle to be begun on the strength of orders originating many hours or even days earlier. When no instant communication was available it placed a front-line commander in an impossible position. He could not delay an advance even though it was outside the bounds of reason to proceed. Because of this sort of position the introduction of radio to the battlefield proceeded apace and by the end of the war quite sophisticated equipment was being used.
In the
environment of a trench it was a trifle uncomfortable when it
came to operating a transmitter. Here an NCO, festooned with cables
is using a medium power trench set precariously balanced on a
packing case covered with a piece of canvas.
This was described
by the vendor as a morse key for a 30watt Trench Transmitter.
Not a simple morse key however as you can judge from its picture!
Or if you could feel how heavy it is!
From what I can gauge from the circuit and instructions,on its lid, the trench transmitter had two main parts. The first is the actual transmitter carrying the valve(s) and the tuning components. The second is the box of tricks depicted here.
Inside is a large, heavy transformer with a 10 volt primary winding and a high voltage secondary (yet to be measured).
Primary current is interrupted by the small springy key in the centre of the inset wooden case. Under the key is an iron core energised by current passing through the transformer primary winding. The device in the centre with the springy key is therefore a buzzer which interrupts the primary current at an audible rate generating an instantaneous high voltage in the valves HT line, generating RF output.
The polished wooden compartment on the left of the lid contains a spare spring and various spare terminals.The leather strap was probably used by a soldier for securing the box to his leg so that when comfortably seated he could operate the transmitter. That is until his leg went to sleep from the pressure of the box!
The strange looking flaps fastened to the box lid are a simple waterproofing arrangement. When new these were stapled down to the wood but when first used the edges were torn away and then loosely dropped down when the lid was closed. This kept out the mud and rain as of course the operator had often to brave dripping mud from the corrugated iron roof of a hole in the side of a trench.
The large label tells
the operator how to connect and check the operation of the wireless
The small label gives
the wiring details.
The connection marked "T.V.T" is a mystery but may stand for "Transmitter Valve Trench".
Was the output keyed by a proper morse key ?
Is the box an arrangement for applying amplitude modulation to the transmitter which is then keyed by a key plugged into the transmitter front panel?
Or is it in fact the generator deriving HT from a set of accumulators ?
I suspect a part of the circuit, opposite, showing the connection from the third pin of the battery plug is missing.
Can anyone, that knows such things from the dawn of military radio, shed some light?
Detail of the buzzer unit for converting the
battery DC into AC before being applied to the transformer. The
adjuster screw is uppermost.See a piece of equipment used for setting up receivers and transmitters in WWI aircraft
Thanks to Bob
Norman for the photo. If you want any medals or pictures framing
he's your man.
This is the British
equivalent.Unfortunately I don't have one of these
however I've now acquired a couple of other types since John Northmore kindly contacted me.
Intelligence activities also proceeded apace, being based on the interception of military radio and telephone traffic. It would be many years though before the words "SIGINT" and "COMINT" would be coined and intelligence would be assimilated and disseminated fast enough for it to make much difference. The first substantal organisation had Bletchley Park as HQ, then later it was GCHQ in Cheltenham. Six key aspects are involved: identification of what to tune in to; interception and storage of information; decryption so it can be read; translation into English; analysis of usefulness and working out who might benefit; and dissemination to customers (which of course usually means encryption).
Alongside developments in communications and advances in the speed of providing information to those who most needed it, were developments in coding and cryptography, aimed at slowing down or completely preventing the gaining of intelligence from intercepts.
This is an amplifier made by
the same firm that designed the cryptographic equipment whose
key was cracked by the Enigma computer at Bletchley Park some
twenty odd years and a war later.When a telephone was used to signal from a WWI trench an earth connection was usually made and through the earth connection a signal flowed into the ground. The majority of the signal took the easiest path between sender and receiver but lots of current also passed by more roundabout routes. Because trenches rarely followed straight lines anyway a good proportion of the earth current was detectable at nearby German trenches and if connections were made to ground at two widely separate points enough of the current was available to drive a sensitive detector. The amplifier shown used four triode valves and was able to amplify tiny intercepted earth currents sufficiently for an eavesdropper to listen in on enemy communications.
WWI phones
WWII
phones
return
to entrance