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überarbeitet am 3.1.2013
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In the years of World War II, the high power shortwave transmitter "Sender Emil"
has been commissioned for the central Air Force Command to direct fighter aircraft
and control flight operations. Although it had a favourable topographic location in the middle of the Alps,
it turned out that this transmitter was not capable to reach all aircraft
and airfields within Swiss boundaries.
So there was a project taken to construct "mountain wireless stations" which acted as
relay stations to optimize wireless signal coverage over Switzerland; the "Mountain
stations" Stephan, Neptun, Fortuna and Theodor were the first of it's kind.
There was a lack of suitable high power shortwave transmitters with large frequency
coverage, so the Swiss Air Force authorities decided to re-use the aircraft wireless
stations SCR-287 of several U.S.A.F. bomber aircraft
which had to make an emergency landing in Switzerland and have been interned during
the war. This equipment has been taken out of the aircraft and was installed in
the mountain stations, Zellweger constructed matching mains power supplies.
After the end of WW II, the Swiss authorities formally paid for the requisitionned
wireless equipment and bought further sets of the same type from U.S. surplus.
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Transmitter BC-375-E,
1500 - 12500 kHz, 6 tuning units
A1, A2, A3, pout ca. 45 - 75 W
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Receiver BC-348 / E-018 / H-Empfänger: superhet, IF 915 kHz
200 - 500 and 1,5 - 18 MHz, analog dial
A1 (telegraphy CW), A2, A3 (telephony)
Mains power supply from Swiss production, BC-221 wave meter for frequency calibration
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The mountain stations usually installed in fortified military buildings in the Swiss
alps could be operated by local personnal and later remote controlled for relay service.
In the transmitter barrack, there were three transmitters BC-375-E (S-018)
altogether with the tuning units and wave meter BC-221,
in the receiving barrack the all wave receivers BC-348,
also calles E-018 or "H-Empfänger" with external speakers and mains power supply
made by Zellweger AG, Uster.
I would be very thankful for further information and images from mountain stations.
further information:
Information from the Swiss Air Force Museum Dubendorf, where the equipment is displayed.
e: Manuals of the U.S.Army for the Transmitter BC-375-E and
Receiver BC-348
© 3.1.2013 Martin Bösch
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