überarbeitet am 31.12.2012
The Swiss Air Force ordered fighter airplanes Messerschmitt Bf 109 E in Germany
in 1938, these airplanes came without a wireless station installed. Also the
fighter aircraft Morane D 3800 produced under French licence by Federal Construction
Works, Thun, from 1939 needed to be equipped with a suitable wireless station.
The evaluation of different aircraft wireless stations for the fighter airplanes
Messerschmitt Bf 109 E und the Morane D 3800 produced under French licence from
1939 ended with two different models. The British ITT Bell R 10-A with four crystal
controlled channels in the VHF band and the continuously tuneable shortwave station
Production progress was very slow, in january 1941, only 13 systems were ready
to be fitted in the D 3800 Morane fighters. The wireless stations turned out to
be unreliable and the frequency stability poor; an improved version was produced
and until the end of 1943, only 28 fighters Morane D 3800 and another 28 Messerschmitt
Bf 109 E could be equipped with the new set. Frequency stability continued to be
a major problem.
The receiver is a superheterodyne covering 2000 - 12000 kHz ab, a 6C5 valve is used as oscillator, a 6L7 in the mixing stage, a 6K7 as IF amplifier, a 6Q7 for demodulation and first AF stage, a 6F6 in the AF output stage and a 6C5 in the beat frequency oscillator for CW reception.
The transmitter has three stages and covers 2000 - 12000 kHz too. A 6L6 valve is used in the oscillator, another 6L6 as frequency doubler and a GOT 100 in the HF final stage. A 6J7 is used in the microphone amplifier, a 6F6 in the modulator stage and another 6F6 in the VOX (voice activated transmit mode) circuitry.
Two independant dynamotors are used to generate the necessary voltages for the receiver and the transmitter.
The three operation frequencies are pre-tuned by ground personnel before
take off; for this, precision wavemeters SFR A 409 D have been used at the airfields.
I would be very thankful for further information and images.
© 31.12.2012 Martin Bösch