Inhaltsverzeichnis
Automatic high-speed telegraphy system MFA
Automatic high-speed telegraphy system MFA; manufactured by Whren- & Apparatefabrik W. Moser - Baer, Sumiswald.
The company Moser - Baer in Sumiswald, where the precision mechanics / electronics company Mobatec and the (central) clock manufacturer Mobatime still exist today, developed a high-speed telegraphy system in the 1940s which was used in the Swiss army in the high power wireless stations M1K and G1.5K as well as in the C-Station of the Air Force.
As Morse code knowledge was still required to convert a morse code telegram into plain text and the quality of the printouts under poor transmission conditions was inferior to listening to the Morse code by a trained telegrapher, the high-speed telegraphy operation mode was cancelled after a few years of experience.
Technical data
- Principle: High-speed telegraphy system
- Morse code transmitter: GS200b
- Printer: SR200b
- Paper tape punch SLb
- Paper tape puller
- Transmission speed: 20 - 900 ZpM
Power supply
- Mains operation: 125, 145, 220, 250 V AC mains supply
Dimensions
- Morse code transmitter GS200b: 420 x 290 x 290 mm; 19 kg
- SR200b printer: 420 x 290 x 290 mm; 23 kg
- Tape punch SLb: 600 x 320 x 350 mm; 37 kg
- Tape puller in accessory box: 495 x 320 x 340 mm; 43 kg
Accessories
System components
In the 1940s, when recruiting the necessary signalmen for the high power stations, it quickly painfully turned out that there was a lack of radio operators well trained in Morse telegraphy. Attempts were made to improve the soldiers' reading and writing speed with compulsory courses and even additional military reserve courses, but the learning curve was not too steep.
The „Hell“ teleprinter system, a quasi-facsimile system with the message directly printed on paper tape, was also used to transmit messages with the high power stations. However, Hell mode often did not perform well as the radio operators lacked operational experience and training and the Lo509/1 receiver used at that time left much to be desired in terms of sensitivity and stability. Hell mode was abandoned as an operation mode a few years after its introduction in 1940 (around 1944); reasonably stable Hell mode connections were only possible on long wave.
To replace the „Hellschreiber“, in 1942 the decision was made to use a set similar to the „Sendegarnitur AMS“ developed by the Moser-Baer clock factory for training purposes also for automated high-speed telegraphy and the order for this was placed with „Moser-Baer“ in 1944.
The high power stations G1.5K (SE-302), M1K (SE-403) and C-Station / G1.2K (SE-404) were definitively converted to Moser-Baer high-speed telegraphy in 1948 and the system was operated for several years. However, the fact that Morse code knowledge was still needed to visually read the printed Morse code was underestimated when the system was introduced. So the inexperienced telegraph operators were still kept busy for a long time analysing the printed strips. Experienced Morse radio operators, and such operators were on duty at these stations, were able to record quite high transmission speeds by ear and write them down just as quickly, so that the delay of printing the morse signals on paper strips could be dispensed with - until the introduction of telephony and (automatically encrypted) teletype procedures, the Signal troops turned back to good Morse telegraphy skills „by ear“ and improved training of the signalmen.
The high-speed telegraphy system consisted of an SLb strip punch, on which plaintext were typed on a typewriter style keyboard and which converted the message into Morse code (using the Wheatstone method: Dot = two opposite punched holes on both sides of the transport perforation, dash = two punched holes offset by one step) on a perforated tape).
The punched paper tape is inserted into the encoder head of the GS200b morse code transmitter, scanned there and the Morse code signal generated in this way is sent to the transmitter's telegraphy relay or a microphone input (A2).
On the receiving side, the Morse code signal from the receiver output is fed to the Printer SR200b, which prints the dots and dashes on paper tape.
The tapes could be inserted into a mechanical tape puller: When a pedal was pressed, the strip was moved past the radio operator's eye for reading, he had to write down the plaintext message on a telegram form.
All necessary ciphering / deciphering had to be done manually using cipher machines or manual ciphering methods.
Technical principle
Tube assembly
Development
In 1942, the KTA commissioned the precision mechanics company Moser-Baer to develop a high-speed telegraphy system, and in 1944 the first series was ordered. The system was shown to the public at the Basel Fair (MuBa) in 1945, but any information about the existing contract with the army was prohibited.
Deployment
A first badge of 60 sets was procured in 1947/49 and a further twelve sets in 1949/51. However, the documentation „Army radio stations“ mentions a number of 49 sets at a unit price of CHF 18'000; the system was used in the high power wireless stations M1K and G1.5K of the signal troops as well as the C-Station of the Air Force signal units.
In 1954, the system was extended by a CCITT to Morse code converter in order to be able to process punched tape from teleprinters. With the introduction of the ETK-R 55 single-tone combination printer, high-speed telegraphy was decommissioned in 1958.
