====== Braille recorder 46 ======
Hell printer **St. aps. 31 a**; manufactured by [[Siemens|Siemens & Halske, Berlin]].

The experience with the "Hell" operation mode was sobering, especially with the [[SE-302|G1.5K]] shortwave station of the early series with the  the [[E-622|Lorenz receiver]]; the use of the [[E41]] single conversion superhet receiver improved the situation but also was a great challenge for station personnel.

At the decision of Maj Métraux, the army's singal chief, from February 1946 on, the use of [[Hell]] transmissions over shortwaves was abandoned and only hand-keyed telegraphy was used; the Hell equipment was withdrawn from the corps material.

However, the Hellschreiber proved itself useful on long-wave connections and especially in the wired network, so that a number of sets of the latest generation were procured again in 1946 to be used in the wired network of the Air Force and Anti-aircraft troops.
{{:images:endgeraete-siemens-hell-st-abs-31a.jpg?direct&600|Siemens St. aps. 31 a}}

===== Technical data =====
  * [[Principle]]: Teleprinter
  * [[Operation modes]]: [[Hell]] (quasi-facsimile system according to Dr Rudolf Hell)

==== Power supply ====
  * [[Mains operation]]: 220 V AC mains

==== Dimensions ====

==== Accessories ====

===== Operation =====
The components of the **Hell teleprinter 46** with the combined transmitter and recorder St. abs. 31a are all housed in a wooden crate.\\ 
{{:images:endgeraete-siemens-hell-st-abs-31a-kiste.jpg?direct&400|Siemens Hell 46: Kiste}}

In this variant of the Hell printer system, the punched tape reader and tape printer are combined in one set.\\\ 
{{:images:endgeraete-siemens-hell-st-abs-31a.jpg?direct&400|Siemens Hell 46}}

Lid removed, over the years the zinc plague has attacked the set.\\ 
{{:images:endgeraete-siemens-hell-st-abs-31a-b.jpg?direct&400|Siemens Hell 46 (open)}}

In a wooden power distribution box, there is the main switch of the system, various sockets can be used to supply the various components.\\\ 
{{:images:endgeraete-siemens-hell-st-abs-31a-Netzschalter.jpg?direct&400|Siemens Hell 46: mains switch}}

The tube buzzer St. sum. 1a produces an audio-frequency alternating current of 900 Hz, to which the Hell signal is superimposed and fed to the transmitter. The keying of the transmitter is done at the grid of the keying tube.\\\ 
{{:images:endgeraete-siemens-hell-st-abs-31a-sum-1a.jpg?direct&400|Siemens Hell 46: Tube buzzer}}

The signal is converted into an audible signal in the receiver by means of a [[BFO]], this audio signal is amplified in the Hell amplifier and fed to the Hell printer.\\ 
{{:images:endgeraete-siemens-hell-st-abs-31a-verst-b1-spez.jpg?direct&400|Siemens Hell 46: Write amplifier}}

If the speed is poorly synchronised, the two printouts of the message run at an angle, but the message itself remains legible. The synchronisation can be adjusted with the speed control until the two print strips run exactly parallel indicating good synchronisation.\\ 
{{:images:endgeraete-siemens-hell-streifen.jpg?direct&400|Siemens Hell: Streifen}}

===== Technical principle =====

==== Tube assembly ====

==== Development ====

==== Use ====
The systems procured in 1946 were probably only used in the wired network of the Air Force.

{{gallery>:images?endgeraete-siemens-hell-st-abs-31a*.jpg&0&80x80&lightbox&showtitle&titlesort}}

===== Technical documentation =====
  * [[https://hamfu.ch/_upload/Albiswerk-Die_Siemens-Hell_Schreiberanlage-1946-web.pdf|The Siemens Hell Schreiber St. aps. 31a, Siemens Albis]]

==== Further information ====
  * [[http://armyradio.ch/radio-d/siemens-hell-schreiber-b.htm|Siemens Hellschreiber 46 at www.armyradio.ch]]
  * [[https://www.hamfu.ch/de/geraete/geraet.php?id=128|Siemens Hellschreiber on the Hamfu website]]