Submarine
Installation - the first submarine so fitted was the B5 -
This was called the Type 'X' Fit. The 'B'
Class consisted of 11 boats all of them obsolete by the start of
WW1. The characteristics were
as
shown below and here is a picture of the B4 [but without
a main roof aerial] her sister boat, with apologies for not
having a picture of B5. The W/T
fit was the same as the
Type
4 Destroyer kit but with some basic alterations to
the circuitry. At all times in a submarine there is a very real
danger of a battery explosion. Like all batteries, they "gas"
and give off hydrogen. Sparks and hydrogen are not good
bed-fellows unless fireworks are the order of the day. Hence,
many of the modifications were addressing the problems of
sparking and brushing. Airtight boxes have been used for The
two-knob Morse key [completely boxed in unlike the surface
version] and have had their respective key-bars extended and
each protrudes through an airlock also to avoid sparking.
Platinum contacts have been used in lieu of silver. Submarines
were given a Tune of 600 feet = 1.64MHz to transmit on and a
suitable receiver with additional tuning so as to receive her
own waves plus that of destroyers and Harbour Defence sets.
Just like a surface ship, the boat had a
W/T office and within, a silent cabinet wherein the operator sat
- it was very tiny! The aerial was enormous and
consisted of a four-fold roof type, which could be lowered from
the conning tower. The strength of a submarines pressure hull
not only depends upon the material used [shape, metal, welding
etc] but on the fewest possible holes being made in it. When
W/T was introduced into boats, a 'deck tube' [to connect the
communications equipment to the aerial] having a diameter of 4
inches was cut through the pressure hull.

If you want to jump ahead to see the submarine aerial
[although you will read about it all when you get to 1913] have
a quick look at page 7 of 12 in file 1913.three.pdf.
HMS Forth, the submarine surface depot ship, has a
Mk1* set modified to operate of 'D' Tune so that she can
communicate with her boats. Look how they have spelt Forth
- in one place as Fourth. A report by the Commanding Officer of
HMS Forth. 1 PO Telegraphist and 1 Telegraphists sent to
sea in B5 to communicate with Forth - good
results.
Diagram showing new Motor Buzzer Set.
Diagram of the Submarine Set. Let me stop awhile to briefly
explain the circuit - I am an ex-submariner so have a vested
interest !
Before we look at the submarine set specifically, let us
consider this drawing to the left. This is how a basic spark
transmitter works. When the Morse key is pressed {**}
AC current flows through the Morse key into the primary circuit
of the transformer. This produces a very high voltage across
the secondary of the transformer. D and E respectively form the
primary and secondary of the oscillator transformer. The circuit
C, F G and D form the sparking circuit and also the oscillator
circuit of a wavelength dictated by the value D. AC alternating
+ and - charges and then discharges the transmitting condenser.
When it discharges, it does so across the spark gap. A high
voltage high frequency oscillating current is transferred onto E
which increases the voltage to a very high level and then onto
the aerial.
Now lets look at the very first submarine installation.
The transmit side can now be completed by using the letter
indicators in the picture above and applying them direct onto
the submarine set. When the Morse key is pressed, contact 1 is
raised to touch contact 2 thereby joining the braiding and the
centre core of the aerial cable together shorting out the aerial
to the receiver. Contact 4 is directly connected to the primary
B so that pressing the key touches contact 3 and current flows
through the primary stage at 48V AC inducing a current into C
the secondary - then see above for the rest of the story.
Contact 6 is permanently connected to the + terminal of a low
voltage DC circuit and on pressing the key the circuit is
completed through contact 5: you will see two lamps in series on
the line between the + voltage and the key position 6 and these
burn accordingly to inform the operator that it is "safe to
transmit". Note the bits and pieces used to cobble this
fit together - "Oscillator T.B.D. Pattern" = Torpedo Boat
Destroyer/also TBD Condenser. "HD Transformer" = Harbour Defence
Set; "HD I.C." = Harbour Defence Set Impedance Coil; on the
receiver "PHD Sliding Condenser" = Portable and Harbour Defence
Set etc. The Type 'C' receiver has two detector options and
tuning arrangements to allow the boat to listening to the
destroyer wave and the Harbour Defence wave. Note the LS of the
oscillator primary = D in the diagram. It is 8.46. Remember
λ [in feet] = 206 x square root of
the LS. The submarine operates on a Tune of 600 feet, so 206 x
2.9086 should equal 600. It does, almost!
Many problems existed, the majority to do with the submarine
operating environment. Distances achieved very short, 1 to 2
miles and at the very best 25 miles [although Defiance
thinks 50 miles possible] where
strength 12 [yes, twelve] was heard. The aerial has
no stays and the masts wobble about all over the place.
It is considered essential that a Telegraphist is necessary
because it is too much to ask a boats officer to come off the
bridge or from the engine room to sit in the silent cabinet and
operate W/T equipment etc etc., especially when he has his own
duties to perform as well. HMS Defiance' comments agree
that a Telegraphist should be a member of a submarines ships
company. |