Autophon got an order to develop an allwave superheterodyne receiver in 1938 an developed the E39 receiver, based on their surveillance and measurement receiver RD2679. The concept of a receiver with a triple main tuning condenser and plug-in coil sets with calibrated frequency charts was based on National's HRO receiver. The core component, the triple - tuning condensator PW-3 with the micrometer dial typical for National's receivers, has been acquired from that manufacturer in the USA.
In the years 1939/41, a total of 99 receivers have been built, the have been used in the Swiss Army until 1963.

The whole receiver came in two army-green boxes, the main receiver case and the accessory case with the coil set drawers and all necessary accessories and spares.
In the main receiver case, we find in the left upper corner of the front panel the mains connector and the socket for the cable connected to the 12V DC power supply in the accessory case.
In the middle, You find the mains voltage selector quite typical for Autophon sets using a plug that has to bee placed in the correct voltage position, and the mains switch.
The measuring instrument can be switched from signal level indication to plate and heaters voltage control, the controls underneath are the tone control and the AGC switch (Schwundausgleich = "Fading correction").

In the left lower section, You find the controls for the BFO (there is also the possibility to regulate the level of the internally generated auxiliary carrier), the Sensitivity ("Empfindlichkeit") and Crystal filter bassband, the volume ("Lautstärke") and bandwidth ("Bandbreite").
On the right, You find the main tuning knob with it's micrometer 000 - 500 dial, this arrangement allows You to retune exactly to a known frequency, but do determine the exact corresponding frequency to the micrometer reading, You have to check the calibration chart - all of these have been drawn by hand for each receiver. Underneath, the corresponding coil set for each band has to be plugged in. Connect the antenna to the red aerial socket.

In an accessories case, You find some drawers containing the plugin coil sets some spares, headphones - there is also a 12V DC power supply converting (car) battery power to the necessary plate / B+ voltages for operating the receiver in this case.

This receiver is a technical marvel - it can be still be used for shortwave reception nowadays, but for "chasing the radiowaves", a receiver with direct frequency readout makes things a lot easier. One technical drawback is remarkable, the single conversion set will get pass the intermediate frequency in the 1,2 - 2,86 MHz range, and reception will be disturbed around 1,6 MHz.