This worn and beaten fieldphone was made by Siemens & Halske in 1929 (based on Capacitor and Generator mfg. date). Maybe it was a PTT lineman's instrument, but more probable it was for industrial type of use, construction, power plant, or also firebrigade or something like that. I did not find yet any sources for details regarding this instrument.
Connectors for an external battery.
Completely disassembled to clean and repair.
Electrical diagram (self made).
Ringer part# F. wck. 39a. F. -> Fernsprecher, wck. -> Wecker (German for Ringer).
Generator bottom, 630Ohm winding, Manufacturing code BK5, B -> Made in Berlin-Siemensstadt, K -> 1929, 5 -> May.
Generator part# F. Ind. 30. F. -> Fernsprecher, Ind. -> Induktor (German for Magneto/Generator).
Arrows indicate where to apply lubricant.
Partly disassembled handset.
The handset is the same type Siemens introduced for the type 1924 PTT standard automatic telephone ZB/SA 24.
But with P.T.T. lever.
2x 500Ohm receiver coil.
Lorenz type tx carbon-granule element.
Made in 1932.
CL. -> C. Lorenz A. G.
D.R.P. -> Deutsches Reichs Patent (I assume).
OB -> Ortsbatterie (German for local battery).
The crank lever with wooden knob.
The instrument uses a standard flashlight type 4,5V battery. this one is a self made reproduction of a 1930ies era Pertrix battery.
The generator takes up the lower part of the body.
Above the capacitor (which blocks the low frequency ringing current from the receiver) and the two winding coil.
The big, loud and robustly built ringer.
The empty leather pouch which shows it's years.
Ready to use.
Ready for transport or storage.
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