The Übertrager is a transformer where the number of wire turns on the primary coil equals the number of wire turns on the secondary coil. In this article, I will explain how the Übertrager is used to complete a connection between a one-wire/Earth telephone line and a two-wire telephone line.
During WW2, the German armed forces typically connected field telephone equipment with one-wire and an Earth ground via grounding stakes. These stakes had a wire terminal for the Lb/E wires on telephones and switchboards. Only the La wire was connected directly to the other telephones and switchboards.
These connections worked, and conserved wire, but “Fiend hört mit.” The enemy could tap into phone calls through the Earth and eavesdrop on sensitive information. For this reason, it was forbidden to use one-wire/Earth line connections within 300 meters of the front line. Near the font line, two-wire line connections had to be used, making it impossible for the enemy to eavesdrop.
If a connection had to be made between a one-wire/Earth line and a two-wire line, an Übertrager was used. This could be done at a switchboard.
For example… Suppose there is a switchboard connected to a field phone near the front line. It is a two-wire connection terminating on Line 8. Suppose the same switchboard is connect to another field telephone well away from the front line. It is a one-wire/Earth connection terminating on Line 9.
Suppose Line 8 wants to connect with Line 9. This is done by hooking up an Übertrager between the two lines. First, the switchboard operator must obtain a Vermittlungsschnur, which is a patch cord with a connection jack at each end. This cord is typically used to connect two FF33 field telephones together, but the jacks also fit the switchboard line sockets and the Übertrager “P” and “S” sockets.
Plug the switchboard line cord for Line 9 into the Übetrager “S” socket. Plug one end of the Vermittlungsschnur into the “P” socket of the Übertrager. Plug the other end of the Vermittlungsschnur into Line 8 of the switchboard. Line 8 can now talk to Line 9.
For more information about the Übertrager transformers and how they are used to make Simplex and Phantom Circuits, check out my new book on WW2 German field telephone equipment… https://www.lulu.com/en/us/shop/rotwang-manteuffel/world-war-2-german-field-telephone-equipment-a-basic-guide-for-reenactors-and-historians/paperback/product-976w9q.html?page=1&pageSize=4
WW2 German Field Telephone Equipment 