Crystal Radio Set 1920's

I have looked everywhere on-line, Germany, Austria, USA, UK, France & Italy with just one hint that it may have originated from German. I found one almost identical but with 2 extra sockets for a plug-in coil and text read make in Germany? The corners were chipped and wiring a mess with a detached aerial coil that was had to see hidden under the tuning capacitor.

I re-wired it using the standard crystal set layout and checked for a signal on an oscilloscope. It the early 1950's similar ones were manufactured also in Germany, but by comparison the parts are all made with modern plastics and not Bakelite like this one, also tend to have coloured knobs on the crystal handle. When I first opened the parcel it arrived in I thought it was a more modern type, it was so shiny for 90 years old, but it soon became clear the components were very old.

This picture shows how small the aerial coil is after I removed the tuning capacitor or condenser as they were known as in the early days of radio. Many condensers and transformers were housed in Bakelite, but a complete radio made from it is quite rare for this period. The coil resistance wise is about 10 ohms, suggesting it must be quite long. The other crystal set example I have is made from pressed Ebonite a material that was also common in components, radio set fronts and rear HT terminal fascias.

The white/blue wire is one that was missing, I'll cover it with cloth sleeve when I get the time to keep it more authentic. Originally most of the wires were held tight a the pot-rivet type fixing of the sockets were applied. I wonder how many boxes were broken while fitting the sockets, quite a skilled job. The tuning capacitor is made from cardboard and brass, and the connection to the center spindle is wired through a loop spring design, another hint of 1920's build. Another harp back to the past is the writing embossed into the Bakelite at the headphone socket, just 'T' which stood for telephones, the word used then for headphones, you must remember that wireless started out as a telegraph system using Morse code. The base cover was missing , looks like when new it was riveted in place, but over the years when going faulty it was forced-off and repaired and got lost. I made a new one from gold reflective card, gives it  a nice brass look. One final caution, if you are using a period crystal it won't work until you find a good place to 'tickle' the cats whisker, it will crackle until you get the connection of the fine wire right, don't forget it will need a long length of wire for an aerial and also a good earth connection, radiator or gas pipe are the popular points - good luck!