1926 · Multiple Valve in One Envelope · Work 806 of 1,871
A small wireless set of 1926 on a kitchen dresser in Berlin, a flat box of dark brown stained wood nineteen centimetres wide, on top at the right in a black holder a tall straight glass tube thirteen centimetres high with a rounded silvery mirrored top, inside it three identical small upright cages of fine wire in a row glowing faint orange, at the left a flat disc-shaped coil ten centimetres across of brown cotton-covered wire in a lattice winding standing on edge, at the front a black knob on a round metal plate with a hand in a rolled-up shirt sleeve resting on it, warm light from a glass ceiling lamp.
What it was used for
The Loewe multiple valve 3NF sat in the Ortsempfänger OE 333, a simple set for receiving the local transmitter. Per the object text of the Museumsstiftung Post und Telekommunikation, one glass envelope holds 3 triodes, with 2 coupling capacitors and 4 resistors sealed in separately. The valve was developed in cooperation with Manfred von Ardenne. The OE 333 was a plain Audion receiver without regeneration, with a two-stage audio amplifier for loudspeaker reception, and easier to tune than a crystal set. In 1926 it cost 39.50 RM; with aerial, loudspeaker, accumulator and battery the total came to about 100 RM.
What was new
What was characteristic was that the whole receiver circuit apart from the tuned circuit - amplifying systems and passive components - sat in a single evacuated envelope. Per Jogis Röhrenbude the reason was commercial: Telefunken held the German tube patents, and the licence fee was charged per tube socket, not per tube, so several systems in one bulb cost only one fee. The barb followed from the same construction: if a filament broke, no single system could be replaced; the owner could send the valve to Loewe for a paid repair. By 1932, per the object text, more than 1 million sets had been sold.
What the sources leave open: The museum object text names no licence fee or tax as the reason for the construction; that explanation comes from collector and technical literature (Jogis Röhrenbude). Production figures for the valve itself are unverified; only the more than 1 million sets sold by 1932 are. Jogis Röhrenbude reads three resistors from the circuit diagram; the object text names four.