Wow, a mystery solved 40 years later!! Found some of these in a box of bits on an RAF base when I was a kid. They were on some signalling gear with headphones m

Wow, a mystery solved 40 years later!! Found some of these in a box of bits on an RAF base when I was a kid. They were on some signalling gear with headphones made of electromagnets and thin circular iron plates in the ear-pieces. The cotton braided wires had been joined with these weird copper pipes and then wrapped around with electrical tape. Obviously a field repair thinking about it now. They were surely the same tech.