Aeronautical Ground Station SE-219
L - Station
SCR - 274-N, U.S. Navy / Aircraft Radio Corporation / Western Electric

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überarbeitet am 5.1.2013

As there was a need of suitable aircraft communications shortwave equipment, technicians of the Swiss Air Force constructed an improvised field ground station from U.S.American "Command Sets" from the SCR-274-N system.


Receiver BC-454: 3 - 6 MHz

Receiver BC-455: 6 - 9,1 MHz

Transmitter BC-457-A: 4 - 5,3 MHz

Transmitter BC-458-A: 5,3 - 7 MHz

A1 pout 40 W; A3 (telephony)



antenna tuner, dynamotor power supply

The U.S.Navy introduced the ARA/ATA wireless equipment in 1940. It has a modular construction and consisted of five receivers (ARA) (one for each waveband) and five transmitters (ATA) (one for each waveband, too) and a separate power supply with a dynamotor.
In 1941, the Radio Set SCR-274-N with nearly identical components with blank aluminum cases was introduced by the U.S.Army Air Corps. This system got the new designation An/ARC-5 after the JAN equipment designations (Joint Army-Navy) have been introduced by both U.S.Army and Navy in 1943. There were additional components added: fixed frequency receivers with crystal controlled channels, VHF transmitter and receiver, homing adaptor, racks and cabling.
Sets from this system SCR-274-N have been in use ob board of most aircraft of the U.S.Navy, in general, they have been addressed as "Command sets".

The receiver BC-454 (3-6 MHz) or BC-455 (6-9,1 MHz) is a six valve superhet: after one RF stage (12SK7) the signal is fed to the mixer stage (12K8), followed by two IF amplifier stages (12SK7/12SK7 or 12SK7/12SF7) and then a detector (12SR7, the second system of the valve is used for the BFO) and at last the AF output stage NF-Stufe (12A6). A dynamotor DM-32 is mounted at the rear of the set to generate the plate coltages.

In the transmitter BC-457-A (4 - 5,3 MHz) and the technically very similar BC-458-A (5,3 - 7 MHz), a valve 1626 is used as oscillator, two valves 1625 are used in the RF output stage and a magic eye tube 1629 to control RF output and for dial calibration by means of a plug in crystal in resonance. This valve is located in the rear part of the receiver and can be observed via a mirror, visible when the hinged cover in the back part is liftet up - a quite peculiar arrangement. The transmitter is powered by a dynamotor DM-33-A (DY-8/ARC-5) located on top of the Modulator Unit BC-456 (MD-7/ARC-5).

All components of the SCR-274-N have been taken out of U.S. bomber aircrafts B-17 who had performed an emergency landing in neutral Switzerland. The sets have been installed in a huge wooden crate to construct an improvised ground station, this got the Swiss designation SE-219 or L-Station.

The equipment was in use from 1945 until 1954.

I would be very thankful for further information and images from field use.

further information:
The station is displayed at the Swiss Air Force museum at Dubendorf.
e: a survey over the SCR-274-N /AN/ARC-5 system in Wikipedia

© 5.1.2013 Martin Bösch