ZB / SAT 19
The ZB / SA 19 (central battery operation / self-connection), ( model 1919, later W19 ), was the first standard desk phone of the German Reich Telegraph Administration . Decisive for the successor ZB / SA 24 , this telephone paved the way for self-connection, i.e. making calls without a manual exchange. The previous model was the ZB / SA 11 , which was introduced before the First World War , and was one of the first self-connecting telephones based on the Hildesheim model 1908 ( M08 ).
General
The designation "ZB / SA" means that the device obtained the power for its carbon microphone from a central battery (ZB) via the telephone network ; In contrast to the local battery (OB) devices, there was no longer any need for a battery at the subscriber or for cranking to generate the call voltage . Thanks to the number switch (dial), the device was suitable for a self-connecting exchange, i.e. for automatic call switching. The participant only had to dial the phone number and was automatically connected to the person he wanted to talk to, as is still the norm today. In the beginning, self-dialing was only possible in the local network . Long-distance connections still had to be switched manually. The expansion of the self-dialing network in Germany took a long time due to economic crises and wars. The last hand-operated local exchange in the Federal Republic of Germany was taken out of service in 1966 .
Appearance
The most important features of a ZB / SA 19 are the first round number switch of the type M21b and the funnel-shaped speech (the so-called "croissant" made of Bakelite ), which proved to be very brittle in everyday use and hardly remained without cracks or chipped pieces. In addition, the device has an external bell on the back of the housing and it can be opened without tools using a rocker lever on the underside . To do this, the fork must first be turned 45 degrees counterclockwise, then it can be pulled off upwards. Furthermore, after removing the housing cover, the number switch can be folded forward by loosening a knurled screw. All model variants have a glossy black painted housing made of deep-drawn sheet steel , some with a logo on the number switch or the housing. The handset ( receiver ) made of nickel-plated brass contains the permanently mounted remote receiver , which consists of two coils on an iron core and a thin sheet metal membrane (magnetic principle). At the lower end is the carbon microphone capsule, which could already be exchanged. Most of the telephones were equipped with the handset 05 (ZB 05), which was designed as the OB05 telephone in 1905. As a result, the voice quality was almost 15 years out of date at the start of production.
Later copies (from around 1924) received the receiver of the ZB / SA 24 , which has a revised, hemispherical projection made of nickel-plated brass with holes without a funnel (see photo), these were also equipped with the following number switch type N24. This has a die-cast zinc carrier plate and is very solid. A few copies that were revised by the RTV in the 1930s (recognizable by the stamp "W19") have built the N30 number switch in the housing, which was used in large numbers in the W28 .
processing
The device is one of the pre-war telephones that were hardly affordable due to their elaborate and at the time advanced technology. One saw him in offices, authorities and with wealthy business people. It took many years before a telephone found its way into private households. The processing of the ZB / SA 19 is so solid and durable that it is still partially functional even after several years in a damp cellar. The paint has been baked in, so the housing is less susceptible to rust.
All components are located on the solid steel base plate and are freely wired with bound cable harnesses .
ZB / SAT 19 today
The ZB / SA 19 is now a collector's item . Well-preserved copies are rare, the costs for such a device are usually. d. Usually to around 250–400 €, most of the devices are in need of restoration. There are several variants from different manufacturers, and consultation devices have also been produced, unlike the ZB / SA 24, there is no luxury version of the ZB / SA 19 with an ivory handle . You can still use it to make calls today, provided that the connection or the telephone system can handle traditional pulse dialing (IWV); otherwise a converter is required. However, the voice and audio quality of the old remote receivers / carbon microphones is poor.
Individual evidence
- ↑ Telephones 1863 to date. A selection from the collections of the museums for communication, Edition Braus (March 2001), 328 pages, ISBN 978-3926318893
- ^ Telephones: Antique to Modern (Schiffer Book for Collectors), Schiffer Pub Co; Edition: Revised. (December 4, 2004), 173 pages, ISBN 978-0764321351