Transmitter FL 40 S / S-300
Zellweger, Uster

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Swiss Army Communication Sets
Synoptic Table
Army Transmitters
S-300 / FL 40 S
S-500 / "Emil"
S-510 / E-646
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überarbeitet am 13.12.2010

Zellweger developed the "Mobile Light" / "Fahrbar Leicht" wireless station in 1940, a core component was the transmitter FL 40 S, the same longwave / shortwave transmitter was used in several variations in mobile and motorized wireless stations.

Shortwave transmitter FL 40 S,

Analog dial, accuracy 1 o/oo of frequency,
frequency ranges 190 - 240 / 240-400 / 400-715 kHz and 1,5-2,3 / 2,3-3,3 and 3,3-4,5 MHz

A1, A2 (900 Hz), A3

pout A1 100 Watts, A3 25 Watts


Shortwave Antennas: 10 m telescopic mast, L antenna
Longwave Antenna: L or T antenna


The transmitter FL 40 S comes in a 37 kg rugged wood / metal case with vents on both sides, which should be opened to let the air circulate during transmission mode.
It is powered from 1250 V DC plate voltage and 300 V DC grid voltage from the rectifier and 3 x 50 V / 160 Hz from the rotary transverter, which is driven from an electric or fuel operated motor. To power the transmitter with the correct voltages is quite difficult, so You have to consult the manual before applying any voltages.
Transmitter FL 40 S, cabinet closed
Transmitter FL 40 S The transmitter covers the longwave ranges 190-240 / 240-400 / 400-715 kHz and the shortwave ranges 1500-2300 / 2300-3300 / 3300-4500 kHz, a crystal permits to calibrate the set for 4000 kHz.
Use the big band selector knob to select the waveband, a small window will show You only the selected band. The main tuning and the fine tuning knob are mechanically coupled.
In the right lower corner of the front panel, You find the modes switch for the operation modes telephony, telegraphy I and II; in the middle between the connectors for the power supply and the microphone / morse key the transmit - receive switch and the high / low power control, You can reduce the output power from 100 W (A1) or 30/25 W (A2/A3) to 1/2 or 1/4, respectively.
With the sets 1-20, You have to operate the transmit-receive switch with all transmission modes, in the sets with serials above 21, in telephony mode, transmit-receive mode is switched automatically when You press the "talk" button on the microphone.
Above the dial, You find the rotary controls for antena coupling and antenna tuning coarse and fine, the meter can be switched to indicate antenna current, plate voltage and plate current.

weitere Lektüre:
d: Die Funkstationen SE-300 und SE-215, Regl 58.113d
d: Website of IgUem

© 13.12.2010 Martin Bösch