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SE-403: M1K

Motorized shortwave station, M1K or SE-403; developed by Telefunken Berlin, manufactured by Telefunken, Zürich; the transmitter was constructed under license from Autophon.

The motorized shortwave station M1K was developed by Telefunken Berlin GmbH in 1941 - 1944, it was called Telefunken shortwave station 1122B.
In Switzerland, the transmitter was built under license by Autophon, the newly developed E44 was used as main receiver and the station was installed on a Saurer M6 or 2CM off-road truck. So the SE-403 became the first Swiss motorized high power station for the signal troops.

Technical Specifications

Power Supply

  • Generator: Power supply unit in a single-axle trailer, three-phase generator (380/220 V, 50 Hz, 15 kVA) driven by a 25 HP diesel engine.
  • Mains: three-phase current 380/220 V, 15 kVA

Dimensions

  • Saurer M6 station vehicle: 6 x 2.2 x 3.2 m; Length with trailer 9.4 m; Weight 9350 kg + generator trailer 2095 kg
  • Saurer 2CM station vehicle: 6.6 x 2.3 x 3.2 m; Length with trailer 10 m; Weight 9100 kg + generator trailer 2095 kg

Accessories

 M1K with it's antenna installed

  • The standard antenna on the truck was the roof antenna, later a rod antenna was used while driving.
  • For fixed operation, a 12 m umbrella antenna or even an elaborate 35 m umbrella antenna could be erected, it could be operated at a distance of 65 m from the station vehicle.

Operation room of the M1K

Station Equipment

The first motorized high power radio station of the signal troops was built on a Saurer M6 truck chassis, the station vehicle had a weight of 9,350 kg, the diesel generator on the single-axle trailer another 2,100 kg. For duplex operation, the receiver had to be operated in a distant location, either remote controlled or in a separate signals vehicle.

The Telefunken - Transmitter As 3028 has a four stage construction, the driver stage can be capacitively tuned in six areas, the transmitter final stage can be tuned with variometers, contact wire variometers are used for antenna tuning.
Three RV12P2000 Wehrmacht valves and one LS50 are used in the transmitter, four LS50 in the driver stage and two RS384 in the final output stage, the transmitter pentodes are grid-modulated.
The station has an output power of 1000 - 1400 W in CW telegraphy (A1) and 300 - 350 watts in modulated telegraphy and telephony.

Initially, the Autophon sm46 all-wave receiver was used as main receiver, it is equipped with a turret tuner and a calibrated frequency dial and exclusively with battery valves D1F are used.
Later, the autophone E-627 was used as station receiver.

Initially, a vehicle roof antenna was used with the M1K / SE-403, later it was replaced by a rod antenna. A 12 m umbrella antenna or a half-wave long-wire antenna was installed for fixed use.

The M1K / SE-403 was the first station of the Swiss Army to use high speed telegraphy „ Schnelltelegraphie - System Moser - Baer“. The relief of the station personnel from morse code training could not be realized. Slow telegraphy operators were able to read the Morse code signs printed on the paper tape only slowly, and some well trained radiotelegraphists could real morse code in quite high speed directly from the headphones.
It was only after the transgression to teleprinter operation with the ETK in 1955, when the requirements for station personnel in decoding Morse telegraphy were no longer necessary.

Technical principle


Technical principle

Transmitter AS60: In the transmitter driver a LS50 works as oscillator, the following stage serves as a separation stage for frequencies from 3 - 6 MHz and as a doubler stage at operating frequencies of 6 - 12 MHz; the two variable capacitors of the tuning unit are in synchronicity. The signal is fed to the transmitter final stage, where another LS50 works as a separation stage for frequencies below 12.5 MHz, in the frequency range 12.5 - 25 MHz, this stage again acts as a doubler stage. In the output stage two RS384 work in parallel. The antenna signal is coupled by a series of selectable capacitors and the antenna is tuned by variometers.

In telephony, the transmitter is modulated via a three-stage amplifier (two RV12P2000 and one LS50 directly on the grid of the transmitter output tubes. In telegraphy, local keying or keying via a DC voltage (operation mode „Fern I“) is done via the keying relay acting on keying valve 1 (RV12P2000). When modulated telegraphy is used (operation mode Fern II, A2), the audio signal is amplified and applied directly to the grid of the first modulator valve.

Receiver: see sm46 resp. E-627

Valve layout

Transmitter if the M1KTransmitter: V1 (LS50, driver stage); V2 (LS50, 1st separation / doubler stage); V3 (LS50, 2nd separation / doubler stage); V4, V5 (two RS384, final output stage);
V6, V7 (two RV12P2000, NF amplifier stages); V8 (LS50, LF amplifier output stage / modulator valve); V9 (RV12P2000, keying valve); V10 (LS50, keying valve).
Stabilizer STV 280/80, iron hydrogen resistor 100 - 300 V, 150 mA.

Development

The Motorized shortwave station M1K was developed by Telefunken GmbH in Berlin from 1941, production began in 1944 and was delayed due to the war. Finally the transmitter was manufactured by Autophon under license as AS60; the Autophon - all-wave receiver sm46 was used as main receiver. The antenna material had to be adapted to Swiss topography, Telefunken Zurich was responsible to install the station equipment in the vehicles.

Field use

From 1947 - 1951, 20 stations were constructed on the base of a Saurer M6 off-road truck at a unit price of CHF 330,000. An additional station was used in Bülach.

The M1K / SE-403 was used for command communications by the Signal Kp of the Field Corps and the Signal Kp of the Army. After the single sideband station SE-222 in 1960 with the signal companies of the Field Corps, all M1K stations were transferred to Signal division 6 and after the radio teletype station SE-415 was introduced, the stations were definitely withdrawn and liquidated in 1980.

Technical Documentation

Additional Informations

en/se-403.txt · Zuletzt geändert: 2019/12/14 08:56 von 127.0.0.1