Hunningscone Patent Wall Telephones (Intercom)

[dsk]

This UK Intercom from around 1920 are quite typical.
Some links: 
http://www.richardsradios.co.uk/hunnings.html
http://www.britishtelephones.com/gec/k040.htm

Pictures and diagram enclosed

dsk

[dsk]

Since this not are mine I would like to get some measurements.
Pleas help to fill out this: encl doc.

Edit: The readings should be made on a single phone, not connected to the other.
Doing the same readings on the other phone makes could help verifying the first readings, but are not a necessity.

dsk

[boombox]

Thanks, Dag.

I'll try and create the circuit you illustrate and take the readings.

Am I correct in perceiving you have shown there are two distinct ways to wire them up and it doesn't matter which way it is done?

[dsk]

Welcome to the forum!

My intention was just to measure on one phone without hooking it up.
(Exception for measurements where strap or battery are mentioned)

I have a feeling of the transmitter could be the faulty part. I have a box of different newer elements who could probably could do the job.

dsk