Presumably the D.Mk.V was developed before, but introduced in 1939 (Release date of Manual; and I have never seen one with an mfg label prior to 1939). It is the successor of the WWI D.Mk.III* which seems to have also been called Mk. IV., eg in the table of contents of [2]. It was also used by the Australian and Canadian Army and other Commonwealth armies. After WWII a good number of D.Mk.V. were refurbished into D.Mk.VI. for the Italian "Esercito di Transizione".
The here documented are a British army set from 1940 made by "P.T.&E.W. Ltd." and a Canadian army set from 1943 made by "P.E.W. Ltd.", both manufacturers are probably the same Phoenix Telephone and Electric Works.
From "Signal Training, Telephone Sets D, Mark V" [1]:
[...] The Telephone Set, D, Mk. V is a portable instrument for field use in Army formations forward of Divisional Headquarters. It provides the following facilities:
The instrument, having a magneto bell, can only be rung by another telephone, or telephone exchange, which has a magneto generator. It can only call by buzzer, which gives visual indication to Switchboards U.C., and aural indication to another telephone when not working through an exchange. [...]
The case and lid are strong aluminium alloy pressings and the lid, when open, gives reasonable protection to the instrument when working in bad weather. A sling is provided, with loops for carrying the earth pin. The battery compartment (for two Cells, Dry, X, Mk. II) is lined with paxolin sheet, and is part of the case. An aluminium alloy platform carries the main instrument panel. This main instrument panel is made of bakelised cambric and on its upper surface carries the buzzer (in its "slide-in" compartment), the morse key, the magneto bell, and the line terminals. On the lower surface are carried the buzzer contacts, the two condensers C1, and C2, the two resistances R1, and R2, the 4-point socket for the handset and the connector for the single headphone. A simple withdrawable bracket is provided for the handset when the instrument is set up for use. A four-pin plug connects the handset to the instrument for working and the single headphone is permanently connected in series with the handset socket. Both the single headphone and the handset pack away in the base of the instrument. [...]
The buzzer performs three particular functions :
From the label inside the lid "Instructions for using telephone sets D.Mk.V.":
To use the set
- See that 2 "X" or "S" cells are connected up as shown in diagram in lid of cell case.
- Connect lines or line and earth to L1 and L2 respectively.
- Plug handset into 4-way jack located below the line terminals.
- To call press the key. When finished give a long dash on buzzer.
To adjust buzzer
- Loosen the collars marked lock and then unscrew centre knobs to clear the armature contact.
- With "buzzer call" key pressed down, advance either knob until the buzzer commences to operate irrespective of quality; lock this knob. Then advance the other knob until a clear, higher note is obtained; lock this knob. Check adjustments by operating the buzzer call key and re-adjust if necessary.
To test instrument
- Disconnect line and earth wires and operate handset (pressel) switch intermittently. Clicks should be heard in both receivers. Press the pressel switch and blow into microphone. The blow should be heard in both receivers. When the instrument is connected to line, the click and blow should be weaker, and under certain line conditions may be inaudible.
- Press buzzer key and touch L1 and L2 with moistened fingers, when the current should be felt. Alternatively, connect the two centre plugs of 4-way plug across L1 and L2 by means of a short length of wire and press buzzer key, when buzzer should be heard loudly in handset receiver.
Always remove handset plug when packing up.
I like the set's design, but the identified unique features are both drawbacks, quite strange design decisions in my opinion:
Disassembled.
This one was made by Phoenix Telephone and Electric Works (P.T. & E.W.) in 1940.
Diagram.
The single headphone is connected in series, so if damaged or missing you have to shorten out this connection.
Instructions for using, adjusting and testing the instrument.
Telephones Hand No. 2, disassembled.
Handset made by Siemens Brothers (S.B. & Co. Ltd.).
Pressel switch.
The transmitter side back opened.
Green/Red are receiver and blue/white microphone connections.
The transmitter side front with cap and capsule removed.
Microphone Capsule Mk. IV.
Receiver side with removed inset No. 1L, cover No. 18 and diaphragm No. 12.
Four point Plug No. 406.
Green/Red are receiver and blue/white microphone connections.
Backside of Plug No. 406.
Receivers, Headgear C.L.R. Single Mk. IV. with removed cap and diaphragm.
Morse/Buzzer Key; D.Mk.V. specific.
Underside of key.
Buzzer T. Mk. I. contacts side.
Made by Siemens Brothers (S.B. & Co. Ltd.) 1939.
Lid removed from buzzer to show the coils.
Top panel bottom.
From the left:
Handset jack assembly (Jacks No. 8) and below headgear terminals.
2 condensers.
Buzzer contacts.
Buzzer contacts labels.
Top panel from top.
From the left:
Buzzer cage.
Screw-holes to mount buzzer key.
Line terminals.
Magneto bell with removed gong.
Top panel from front.
The condensers C1 0,5uF and C2 2uF are stacked on top of each other.
Empty aluminium case.
Open battery compartment.
Battery elements inserted.
On the inside of the battery compartment lid there is a small diagram detailing the battery conections.
Spelling alphabet (type 1938) mounted behind slide out handset cradle.
Set ready to use.
The open lid gives some weather protection.
The lugs on the roght side of the strap are for transporting a ground rod (missing here).
Handset and headgear stored in lower compartment.
Ready for transport.
From the back.
The belt straps have deteriorated.
The holed on the left are not original, not clear what they have been added.
(To bring wires in from the back?)
Canadian instrument disassembled.
Made in 1943.
Diagram.
Instructions for using, adjusting and testing the instrument.
Canadian handset of same type than TS-9-(*) used on US EE-8.
Telephone Hands No.2, Canadian.
Standard US/Canada HA1 style receiver element, 1943.
Hedgear C.L.R. made by Northern Electric (N.E. Co.).
Headgear receiver with removed cap and diaphragm.
Buzzer T.Mk.I. Canadian, made by Northern Electric (N.E. Co.) 1943.
Spelling alphabet (type 1943) mounted behind slide out handset cradle.
Ready to use.
Handset and headgear stored in lower compartment.
Ready fro transport.
C around broad arrow indicates a Canadian army instrument.
From behind.
With belt straps.
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