Fahrbar Leichte Funkstation 19/25
Funken - Kleinstation GFuk 18
Telefunken GmbH, Berlin / Telefunken AG, Zürich

Telefunken Logo
Swiss Army Communication Sets
Synoptic Table
Army Transceivers
Transceivers SE-1xx
Transceivers SE-2xx
Transceivers SE-3xx
Transceivers SE-4xx
FL 19 / 25
SE-300 / FL40
SE-301 / FS25
SE-302 / G1,5K
SE-303 / G3L
SE-304 / A-Station
varia / copyright
about / contact

überarbeitet am 6.1.2015

After World War I, the Swiss Army needed to purchase new equipment for "spark telegraphy", because of a lack of funds (Switzerland was quite a poor country with an economy mainly based on agriculture, then), the Signal Command decided to buy a number of six wireless stations on single axed horse driven limbers.
Going with the rapid progress in wireless transmission technology, the first six sets have been improved and in 1925, another ten sets have been ordered, all sixteen stations then got the designation F.L.25 (Light Mobile (Wireless Station) 25).

Mobile long- and mediumwave station with seprate transmitter and receiver,

Transmitter: Telefunken Spark Gap Transmitter 0,4 TV (1919) resp. Vaccum tube transmitter ARS 87 (1925): 187,5 - 790 kHz
Receiver: Telefunken E213a (ab 1919), replaced by Spez 7Bs (1926) an later by Spez 470 Bs (1932), 100 - 1091 kHz

CW (A1), A2 (with ARS 87 transmitter)

pout A1 75 W (ARS 87)

In 1919, six stations "Funken - Kleinstation GFuk18" (Spark small station GFuk18) have been orderen from the German "Deutsche Gesellschaft für drahtlose Telegraphie, Berlin" (German society for wireless telegraphy), the later "Telefunken" company.
The station, intended for mobile use, was constructed on two limbers pulled by a horse or an open truck: The "apparatus trailer" and the "mast trailer" with a telescopic antenna mast.

In the first years, the transmitter used was a Telefunken Löschfunkensender 0,4 TV (Telefunken Sparc Gap transmitter 0,4 TV) for telegraphy B2. This could be tuned in the 187,5 - 2000 kHz range, the nominal output power was 400 W, primary power 1000 W.
Fl 19 (alt)
(F.L. 19, early setup: Receiver E213a (right lower corner), AF amplifier Spez 60 Bs (two valves, left upper corner), Wavemeter (left lower corner), Transmitter 0,4 TV (right cabinet); image from a publication from R. Ritter)

When the signal troops equipment was renewed in the year 1925, the existing F.L.19 stations were improved and ten new stations were ordered: The transmitter with the new arrangement was a Telefunken valve transmitter Zwischenkreissender ARS 87 for telegraphy A1 (CW), A2 and makeshift telephony A3. The transmitter covers the 187,5 - 790 kHz frequency range and has an output power 75 W.
The valves used are a triode RS 19 and a triode RS 55.

Tfk - Empfänger Spez 7 Bs Tfk - Sender ARS 87
Receiver Tfk Spez 7 Bs Transmitter Tfk ARS 87 (Both images from a Swiss private collection)

In the early setup, the receiver used was a Audionempfänger E213a (Tuned radio frequency with regeneration) covering the 86 kHz - 2000 kHz frequency range, in this receiver, two triode valves RE 11 are used.
In 1925/6 this receiver has been replaced by the Zweikreis - Reflexempfänger Spez 7 Bs (E25) (two tuned circuits) covering the 125 kHz - 2000 kHz frequency range. In this receiver and the audio amplifier (in a separate wooden cabinet), four triode valves RE 062t are used.
In 1931/2, the receiving equipment was replaced by the Telefunken 470 Bs (E31), a very modern and sensitive set in it's years. It came with six triode valves RE 074n and has a frequency coverage of 100 - 1090 kHz.
F.L.25 mit E31
(F.L. 25, late setup: Receiver E31 / Spez 470Bs (left lower corner), a Wavemeter Spez 125Bs (left, on top of it), Transmitter 0ARS 87 (right cabinet); image from a publication from R. Ritter)

The aerial used was a umbrella antenna on a15 m telescopic mast mounted on the back trailer or a 60 m T or L shaped double wire antenna erected between two 12 m masts.
F.L.19, zwei Protzfahrzeuge
(K+W official image reprinted in a publication from R. Ritter)

The station was powered from a fuel operated generator.

The "Fahrbar Leichte Funkstation 25" has been finally replaced by the FL 40, constructed by Zellweger, Uster in the year 1941 and want completely out of service after the end of World War II general mobilisation.
F.L.19 Station
(image reprinted in a publication from R. Ritter)

further reading:
d: Das Fernmeldematerial der Schweizerischen Armee seit 1975, R.J.Ritter, Folge 6
d: F.L. 19 / 25 on the website www.hamfu.ch of IgUem

© 6.1.2015 Martin Bösch