Wireless of the Week - week 39
It’s common today to send multiple signals over a single metallic or fiber optic line, yet that technology was innovative in the late 1920’s when it was applied to military line signalling. The advantages were obvious: if one line could carry more than one signal, the resources and manpower to string and maintain that line could be optimized while a greater number of troops could communicate with each other. Two such line sharing devices are presented this week, a ‘Switches, 3 Way R.A.’, a simple splitter, and a more complicated ‘Superposing Unit 1 Transformer’.
The Switches 3 Way R.A. was primarily used to split one incoming line to three phones, one for each gun in a Royal Artillery half battery. Each phone could then receive and send messages when the operator set the corresponding switch from ‘Normal’ to ‘Connect’. The outlying phones could in turn be connected to additional lines linking the three phone assemblage and its exchange to additional line devices. The unit came in a wooden box 8” wide by 5-1/8” tall by 5” deep. It had a web carrying strap fixed to the top and a side panel opened to reveal the 3 switch controls and wire binding posts. A paper wiring diagram was glued to the inside of the lid. Holes for the incoming wires were proved on each end and the lid could be closed for some protection against the elements once the switches were set according to need.
The Superposing Unit 1 Transformer was one of a number of units that used an internal transformer or transformers to alter the current of a line signal allowing it to be sent, or superimposed, over the same line as another traditional telephone device. The Superposing Unit 1 Transformer was designed for use with a Switchboard, Universal Call 6 Line, however it could be used on a 10 line switchboard or with Frames D and P, 10-wire, Mk.1 and Mk.1*. It comes in an aluminum alloy case 4-1/2” wide by 4” tall by 3-3/4” deep. The lid had a tab on its face to attach it to the left side of the switchboard. The superposing unit itself was then inserted into the lid and the same retaining clips that held the lid on were now used to hold the unit into the lid and therefore onto the switchboard itself. Once open and attached, the binding posts to connect telephones or Fullerphones were accessible. Dummy sockets for the attaching line and instrument plugs were also provided. As is typical, a wiring instruction plate is riveted to the inside of the lid.
The manual says the unit provides: i. Superposing a series Fullerphone on a telephone circuit, ii. Superposing a phantom to earth Fullerphone or telephone circuit to a twin line, iii. Superposing a Fullerphone or telephone phantom circuit on two twin lines, iv. Further developments of the phantom arrangement where possible and v. In cases of ii and iii above, providing for an intermediate Fullerphone or telephone station on a phantom or phantom to earth circuit…which suggests a large number of confused young signallers spent a great deal of time studying the use and operation of these units.
No maker names or acceptance marks are on either unit which leads me to believe they are both British made.
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11-11-16, 00:59
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