RNF7 Loewe Radio 1926 three-in-one tube a design by Manfred von Ardenne

Description

Loewe introduced this three-in-one tube in 1926, a design by Manfred von Ardenne. The construction is unique because the tube not only contains three separate electrode systems, but also the associated resistors (4 pieces) and capacitors (2 pieces) that are normally required for a 3-tube receiver. Only the tuning means are not located in the casing. The two preamplifiers are mounted horizontally at the top of the tube, the output stage is placed vertically just below them. To prevent contamination of the vacuum within the tube, each capacitor and each resistor is separately enclosed in its own glass tube. The entire system of electrodes and components is supported by a complicated structure of glass rods and metal wires. The original Loewe multiple tubes are true masterpieces of glass technology, but are extremely laborious to produce. Later versions therefore used mica supports, with the glass tube being painted aluminum in order to disguise the less elegant internal structure. The complete system forms a 3-stage RC coupled l.f. amplifier, with an amplification factor of 3000. Loewe designed a special 6-pin bayonet type 3NF for this purpose. This tube is labeled “British made”. Loewe probably manufactured radio tubes in the United Kingdom in 1926 under the brand name Loewe Audion. The manufacturer was the Audion Radio Co.