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überarbeitet am 11.1.2013
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Zellweger, Uster, developed their "Mobile Light 40" / "Fahrbar Leicht" shortwave station in
1940, this station came into service 1941/47. on two limbers, one axed carts, the so called
"vegetable cart" - opened at the back, the wireless station looked like
the booth of a vegetable trader on a market.
All components of this station, specially the transmitter, the all wave receiver 41
and the rectifier and the inverter were used in various wireless stations,
some of them motorised.
The original FL40 on it's trailer got the SE-300 designation after 1951.
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The transmitter FL40 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.
The transmitter covers the longwave ranges 190-240 / 240-400 / 400-715 kHz and
the shortwave ranges 1500-2300 / 2300-3300 / 3300-4500 kHz. |
The Receiver "Uster" / E41 is a single conversion
superhet on frequencies below 12 MHz and double conversion on frequencies above.
Band switching is done like with National's HRO receiver by changing plug in coil
sets. In this receiver, battery tubes, mainly of the type KF3U are used. |
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In one case, antenna wires and counterweights for the longwave and shortwave
antennas are stored. There are two more cases with antenna material, a telescopic
antenna mast is mounted on the trailer. |
As an alternative to the operation from accumulators and an inverter,
Zellweger constructed a mains power supply to power the E41 directly, a few years later. |
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The inverter is intended to power the receiver E41 with the plate voltage of
120 Volts and the heaters voltage of 6 Volts when the main generator of the
station is not iuse or when the receiver is used at the remote location and
powered from accumulators. |
The rectifier is used to generate the plate and grid voltages of the station
from the three phase 50V / 150 Hz current from the generator: 1250 and 300 Volts
plate voltages for the transmitter, 120 Volts plate and 6 V heaters voltage
for the receiver and 6 Volts to charge the accumulators. |
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The three phase power 50V / 150 Hz is generated in the rotary generator,
it can be coupled to a fuel operated or an electric motor. |
The accumulator charger isused to charge the Ni-Fe or
Ni-Cd accumulators of the station with a maximal current of 10 Amps. |
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| The remote unit at the receiver side looks
like an army telephone, next to a standard telephone headset, a pair of headphones,
a microphone and a morse key can be connected to it. |
At the transmitter site remote unit, the morse code or voice signals can
be fed to the transmitter. It also con be used for service communications like
a normal army telephone. | |
© 11.1.2013 Martin Bösch
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