The Large Shortwave Station G1,5K has been developed by C. Lorenz AG, Berlin, in around 1933/34; it has been built by the Lorenz - branch Standard Telephon & Radio AG at Zürich in 1935/37. The station got the designation G1,5K (Gross / Large - 1,5 Kilowatts - K / Shortwave) with the Signal Troops and "B Station" with the Air Force Signal Command.

The three stage Lorenz transmitter can be tuned in four ranges from 1090 - 6700 kHz, variometers are used for antenna tuning. In the transmitter the following valves are used: in the driver stage a RS337, in the intermediate stage two RS377, in the output stage two RS329g, in the modulation and keying stage two RS382 and three rectifiers RGN2504, in the microphone voice amplifier stage two RS282 and three RE084k. The transmitter covers the frequency ranges 1090-1930 / 1930-3430 / 3430-4830 and 4830 - 6700 kHz, dial accuracy of the analog dial is 1 %o, a luminous crystal is used for calibration at 3000 kHz. The transmitter output power ist 1500 Watts CW and 500 Watts in modulated telegraphy and telephony.

The receiver used in the early years with the stations no. 1 - 14 was the two tuned circuit TRF All Wave Receiver EO509/I made by C.Lorenz AG. This battery valve receiver turned out to be unsensitive on shortwavex and made reception in Hell mode extremely difficult. So it was replaced by the All Wave Receiver "Uster" / E41 in stations with number 15 and above.

In the document folder "Funkstationen der Armee" is mentionned, that stations number 1-6 and the "B Stationen" of the Air Force were equipped with two Autophon Allwellenempfängern E44 and the stations 15-28 as well as 32-34 with two Allwellenempfängern "Uster" / E41.

In 1956, the station G1,5K was improved with the new receiver Autophon E-627 and the Telecrypto 53 / ETK combination for automatically encrypted teletype operation. The transmission quality often suffered from synchronisation errors which caused decryption faultsm this was not really improved after the receiver was replaced by the Siemens E-311 / E-645. Radioteletype operation with automatic encryption became much more reliable after the introduction of Krypto-Funkfernschreibers 58 with it's capability of automatic synchronisation.

In the early years, not only telegraphy and AM telephony but also radioteletype Hell, in fact a radio-facsimily transmission mode, was intended to be used. The "Hell" printer developed by Siemens Hell-Schreiber prints out a text directly lisible on paper tape. As the shortwave communication quality strongly depends on propagation conditions, using the Hell mode was quite challenging for the signalmen operating the station.
So even during World War II, the decision had been taken to abandon the Hell mode and to use high speed telegraphy instead: The station G1,5K saw the introduction auf automatic high speed telegraphy Moser-Baer.

A major breakthrough with higher transmission speed was the introduction of the radioteletype system ETK developed by Dr. E. Gretener AG in the years 1955/56. With the ETK teleprinter and the Telecrypto 53 ciphering machine, even automatic encrypted radioteletype communication was possible.
The things really were made easy with the introduction of the KFF-58, the crypto radioteletype machine developed by Gretag with automatic synchronisation.

The station G1,5K is powered by a four stroke fuel motor operated generator providing 15 kVa three phase power, this was installed on the "machine trailer".