Marconi MIKROFON TYPE 158 MARMORBLOCK CARBON 1923’

Here instead we go on heavy ...( in every sense of the word ) square unit of white Carrara marble , with inside a quantity of coal dust ( looks like graffite to me ) .. always of German production early 1920s" as it is marked D.R.P.... Used perhaps in the early broadcasting of radio and/or television audio ... museum item ...if you are not interested in this item change page , if you are more interested in a U47 you will find that in my collection too , however hurry because there are only a dozen left ....