Sorry I'm writing in English, because my Swedish is not so good.
I beleive the small radio receiver on the desk is the the one Nazi's have produced during the 2nd WW, and it was named a sort of Volksempfaenger.
It was a simple so called "audion", "superreaction" or "superregenerative" type of receiver, as a main difference to the already known "superheterodyne" principle. The "audion" type was adopted mainly because of its simplicity, and because it was meant to receive only a local broadcasting, as Nazis didn't want the people to receive the foreign stations! I'm not familiar what type of electronic tubes were used, but two or one combined tube, plus rectifier, were enough for that construction.
The receiver also used an electromagnetic type of loudspeaker, with a permanent magnet. The static coil, supplied with the audio signal, was magnetizing a movable soft iron arm moving in the magnetic gap of the horseshoe formed permanent magnet. The moving arm was connected to the loudspeaker membrane via a metal rod.
The receiving AM frequency selection was adjusted with one variable capacitor, while the other was used to adjust the amount of positive reaction, what had to be done every time the received frequency was changed. The purpose of the reaction was to increase the selectivity and sensitivity of the so called audion stage. The input circuit most probably used is similar to the one shown in Wikipedia, under "Regenerative circuits" section. Actually, part of what I wrote before is also mentioned in the History part of that section.
The housing of the receiver was made of black or dark brown thermosetting material known as "bakelite".
I newer had one, but as a kid remember seeing the parts of it.
Hope you'll find that interesting, BR!