A tube receiver is a radio receiver which, in its electronic circuit predominantly electron tubes as active components used for signal processing. Tube receivers were practically completely replaced by transistor radios from the late 1950s to the mid 1960s .
The first German radio tube receivers were presented in Berlin in 1924 at the 1st Great German Radio Exhibition and, by the end of the 1920s, replaced the detector receivers , which only allowed headphone reception. The number of electron tubes used in the receiver was an important quality criterion, as it gave an indication of the switching effort required - particularly high-quality devices were later given a special display tube known as the “magic eye” as an optical tuning aid . A well-known tube receiver from the early days of radio broadcasting is the 1933 presented Volksempfänger .
Tube receivers were built well into the 1960s, before the transistors replaced the tubes - with them the era of mobile transistor radios (also known as portable radios ) began in the late 1950s , which in terms of miniaturization, power and weight savings, all designs with the up to then surpassed conventional battery-operated miniature tubes.
The number of tubes was - like later the number of transistors - a measure of the reception quality of the device. Shortly after the Second World War, the Soviet military administration in Germany (SMAD) confiscated all radio receivers with more than three tubes in their zone . Only certain politicians and officials were allowed to keep such devices in order to receive special news broadcasts from the non-Soviet controlled area. All the others were left with three or fewer tubes only to receive the German radio station and Berlin radio that were censored by the occupying forces .
In the transition to semiconductor technology , radio sets were equipped with both electron tubes and semiconductor components such as tip diodes and transistors . In these so-called hybrid receivers, tubes work in the high- frequency section , and transistors in the low-frequency sections.
In contrast to transistor radios, tube radios have some disadvantages:
Since the tubes only work after a warm-up phase, tube radios need a few seconds after switching on before something can be heard. The radios are big, heavy and have a comparatively high power consumption. However, the size of the case usually had a very positive effect on the sound ( baffle principle ). Portable tube receivers can only be operated with batteries for a comparatively short time due to the high power consumption ; batteries with high voltages, the so-called anode batteries , are also used. The mobile tube receivers built from the 1930s and used in the first car radios , among other things , were relatively heavy due to the complex generation of the necessary high anode voltages using chopper or single-armature converters . In addition, the lifespan of the electron tubes, especially those in the heavily loaded loudspeaker output stages , was comparatively short. Nowadays, collectors of tube radios have problems obtaining certain spare parts, e.g. B. the magic eye type EM34 is hard to come by.
"Recreation on the banks of the river": family with KdF car and portable tube receiver (around 1940)
Inside of a Telefunken tube receiver
- radiomuseum.org , extensive site with information about all devices
- roehrenradios.de History of broadcasting in Germany 1923–2000