Fullerphone details needed

[Chris Suslowicz]

Originally Posted by David Dunlop

Thanks, Roberta.

The detail bits for wireless equipment never ceases to amaze me. In these parts, I have never seen a fullerphone sold with a ground spike, so I guess somewhere there must be boxes of them waiting to be discovered.

David

One reason for that is because the fullerphone wasn't used in the same way as during WW1; it was mainly intended for static warfare in the "danger zone" where earth return circuits could be easily intercepted using a couple of earth pins and an amplifier. For WW2 things were a lot more fluid and the forward positions mainly used Telephone Set 'D' with twin cable if possible (in India they were restricted to earth return circuits a lot due to cable shortages and the speed of the advance). One major use of the fullerphone was on "phantom" circuits between headquarters and signal centres for passing routine (and coded) traffic. (Using a "Superposing transformer" you can piggyback a DC telegraphy (fullerphone or teleprinter) on top of a speech circuit without mutual interference. The ideal setup is two 2-wire circuits, followed by 2 wires and an earth return, with the last resort being the fullerphone in series with the telephone on a single wire and earth.

The 10-line UC switchboard had an optional "superposing unit 3 transformer" that allowed 3 fullerphone or teleprinter circuits to be piggybacked on any of the 10 lines (1 per line, naturally!).

Chris.