Air Raid Warning Communications System
S-510 / E-646
Zellweger, Uster

Swiss Army Communication Sets

Survey Synoptic Table

Army Transmitters

FL 40 S / SE-300

S-500 / "Emil"

S-510 / E-646

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überarbeitet am 13.12.2010

An "Air Raid Warning System" similar to the "Alert and Warning Net" of the U.S. Army has been installed after 1961. As standard high power transmitters and receivers E-627 have been in use, without capabilities of selective call or muting of the receivers between the messages, many messages were missed because the receiver's volume was turned down the whole day long ond the operators missed the scheduled bulletins.
Twenty years before, the "Alarm Network" based on E-45 receivers, which also could be muted in idle times, already had these selective call capabilities.
As there was no commercially available system, the GRD called for offers from different companies and finally placed a contract with Zellweger Uster to construct one transmitter and five receiver prototypes until the end of 1973, it was not before late 1978, when the improved prototypes were found ready for use with the troops. In the meantime, most of the communications between army groups had shifted to microwave communications, so only the Anti-Aircraft Troops were equipped with the new system.

Shortwave transmitter, Decadig knobs frequency selector, accuracy 1 kHz, frequency range 2 - 11,9999 MHz A3E, A3JU / A3JO upper / lower sideband, F2B selective call system pout 400 Watt A3J	Sensitivity Selectivity under standard conditions used with a dipole antenna with a central pole with automated antenna tuner AG-510/430.

The shortwave transmitter S-510 has been used for long range communications in the "Swiss Air Raid Warning Network" operated by the anti-aircraft troops, the receivers placed in the command posts usually were muted and were called by a selective call system which could adress eight different receiver groups or all receivers at the same time. Messages could be transmitted in AM or single sideband mode.

The complete communications system consists of a transmitter control unit BG-510, connected to the remote transmitter site via field telephone lines.

The transmitter site equipment consists of the transmitter S-510, it's separate power supply SG-510 and the automated antenna tuner AG-510/430.

The speaker's microphone is connected to the transmitter control BG-510, from there the frequency and the receiver group address is selected. The transmitter is tuned to the operation frequency within a few seconds fully automatically.

The receiver E-646 also constructed in a similar design by Zellweger, Uster, can be powered from batteries or mains and is equipped with an external speaker to be placed in the command post room. It can be run from batteries over several days, when it is in muted operation.

© 13.12.2010 Martin Bösch