Field phone and switchboard inter-operability

[Chris Suslowicz]

Originally Posted by Ron King

I have recently acquired various field phones and trying to sort out the same questions
I have 2x 1918 model.D mk2 buzzer units....extremely fragile due to age.......but I think I will get them going.......L1 ..and then CL and then LorE..........three connections has got me lost

Ah! This is fairly simple:

L1 is the telephone line
L or E is the other telephone wire if it's a pair, or Earth if you're using a single wire and earth return (wire to a ground spike "Pins, Earth, Small" or the "heel attachment" on one of your boots - the latter was mainly for line-laying parties).
CL is "Condenser to Line" - for "piggybacking" a telephone circuit on a DC Telegraph wire (usually railway telegraphs in the outer parts of the Empire); it blocks the DC signalling voltage and prevents interference to the Telegraph or the telegraph traffic causing interference to the telephone.

There should be circuit diagrams for the D2 in "Instruction in Army Telegraphy and Telephony Volume 1 - Instruments" the second (1916) edition is probably the best. WS19 group has a copy in the archive. (I've still not found the Signal Training Part III (Instruments) that followed it.)

https://royalsignals.org.uk/signals.htm

(Follow the instructions on the main page when requesting documents; it's a bit fiddly due to relentless abuse by various pirates, etc.)

Have a model L that works and about 4x Model F mk2 that work.( trying to get another Two working)
I am guessing buzzer phones may still ring /buzz bell on some magneto phones.

This is very unlikely. The early "Buzzer Switchboards" used a "Watch Receiver" (i.e. earpiece) to alert the operator. The Telephone Sets 'D' (all marks) were similar, with a single earpiece on a headband for the operator to wear continuously. The D Mark V added a magneto bell for compatibility, and the Mark V* deleted the single earpiece (and should have a wire link across the terminals or the handset earpiece won't work).

Have Australian 10 line no2 switch board.......similar to the UC10.
Relay indicator flaps on switch board are very sensitive.........buzzer phone should trip them.

The Switchboard "Universal Call" (6 or 10 line) was designed to work with both buzzer and magneto calling, but the relays/indicators need careful setting up - there should be "go" and "no-go" resistors clipped inside for setup purposes (to ensure the indicators operate with a buzzer call).

This is all a new item of learning for me.........challenge to get them working.
Ron.

Have fun!

Chris.