Vehicle Wireless Set SE-400 / FIX

At the occasion of the renewal of the Swiss Army signalling equipment in 1946/49, american equipment has been acquired in large quantities from U.S. Army war surplus.

The U.S. Signal Corps station SCR-608 was the first transceiver using the VHF frequency range for military communications and using frequency modulation. The equipment got the designation "FIX" in the Swiss Army, after the introduction of the new naming scheme, it was changed to SE-400.

The set covers 20 crystal controlled channels in the 27 - 38,9 MHz frequency range. In the SE-400 variant, the frequency tripler stage was followed by the frequency doubler stage, in the SE-408 variant, the frequency doubler stage was switched before the frequency tripler, so the frequencies of the 20 channels are found in the 20 - 27,9 MHz shortwave range.

The SE-400 or the U.S. Army Radio Set SCR-608-A consists of two receivers BC-683-A and one transmitter BC-684-A mounted on a mounting frame FT-237. In standard use, the set is powered from 12V DC from the vehicle battery, a dynamotor is used to generate the necessary anode / HT voltages.

On the Transmitter front panel, You find the pushbuttons for the ten crystal controlled channels, the necessary crystals are plugged in behind a cover just left of them. A switch below the channel pushbuttons acts as transmit - receive switch.
At the right, just below the instrument that can be switched to tune the set and to display the antenna current, You find the main switch and the switch to use the amplifier as an on-board intercom on the vehicle.
The front panel of my set has french language lettering, I have no idea whether the lettering language has been changed in Switzerland or whether the set itself came from a French contractor.
The transmitter contains seven valves 1619 and a 1624 as R.F. final. Spare tubes are stored inside the transmitter's case.

The Receiver has a big speaker behind an impact protection cover. The knob VOLUME in the centre of the front panel controls the A.F. gain. The ten pushbuttons are used to select the stored frequencies, when the small button "PUSH to TUNE" is pressed, You can use the thumbwheel to tune the receiver continuosly.
In the bottom row of controls, You find the antenna and earth connectors, the switch for tuning and fixed frequency mode, the switch to select the audio when the system is used as on-board intercom (in a tank) and the squelch control.
The valves are a 6AC7 (R.F. amplifier), 6AC7 (modulator), 6J5 (R.F. oscillator), 12SG7 (I.F. amplifier), 12SG7 (I.F. amplifier), 6AC7 (limiter), 6H6, 6V6-GT (A.F. final), 6SL7-GT (AVC, Squelch), 6SL7-GT (1st A.F. stage and I.F. oscillator).

A view inside the transmitter:
SE-408 inside

With the Swiss Army, the set has been used onboard the "Dodge CC" / "Dodge Command Car" (probably Dodge model WC-56), this (partly open) vehicle has been referred to as "gazebo" in Switzerland.

SE-400 / FIX U.S. Signal Corps SCR-608

SE-400 / FIX
U.S. Signal Corps SCR-608