In Part 2 we looked at a schematic for the Vermittlungskästchen and learned about how it works. In this article, we’ll look at how to connect a headphone or an auxiliary speaker to the Vermittlungskästchen. We will also look at how to terminate single wire telephone lines and double wire field telephone lines on linked Vermittlungskästchen.
If you remove the indicator relay, you will notice that it plugs into a socket identical to the socket for a headphone or auxiliary speaker.
Therefore, you can plug a headphone or an auxiliary speaker into the Vermittlungskästchen. The headphone or speaker will only work as long as the Kellogg Switch is in the neutral position and there is no plug in the VK jack socket.
The Vermittlungskästchen La and Lb/E terminals can be used to terminate single wire + ground or double wire field telephone lines. On each module, there is a little writing tablet in a bracket above the Kellogg Switch. One side of the tablet is white. This is to label a module connected to a double wire line. The other side of the tablet is red. This is to label a module connected to a single wire + ground line. Modules with red tablets must use an Übertrager to connect with modules having white tablets.
A little bit about acquiring Vermittlungskästchen modules… They are very difficult to find, and when they become available, they are VERY expensive. Also, they are almost always missing the indicator relays.
For more information about modular switchboards, and field switchboards in general, check out my book: 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 