Inhaltsverzeichnis
Multi-channel device MK II
Multi-channel set MK II or MK 2, company designation ZT 11e; manufactured by Brown Boveri.
Around 1946, Brown Boveri developed the MK 2 multi-channel adaptor to utilise a microwave relay connection for the simultaneous transmission of several telephone calls. So up to six voice channels can be transmitted simultaneously ober one microwave connection.
The MK II could be used with the TLD (SE-213) and HK-1 directional radios.
Technical data
- Principle: multi-channel adaptor, frequency multiplex
- Operation modes: Telephony, telegraphy
- Frequency range: 35 - 65 kHz (carrier frequencies 40, 45, 50, 55, 60, 65 kHz); transmission in each case in the lower sideband 0.3 - 3.4 kHz
Power supply
- Mains operation: 110, 125, 145, 205, 220, 230, 250 volt AC mains, voltage stabilisation by Mains regulator ZT 11h, ± 15° in each case.
Dimensions
- Three chests, each 630 x 1520 x 380 mm, 125 kg
- ZT 11h mains power regulator: 430 x 360 x 260 mm, 22 kg
- Relay amplifier ZT 11g: 430 x 360 x 260 mm
The total weight of the system without cable and accessory boxes is 397 kg.
Accessories
- Mains controller ZT 11h
- Relay amplifier ZT 11g
Operation
The multi-channel adaptor MK II comes in three cabinets. With a weight of 125 kg each, the system is hardly transportable and could therefore only be used in a fixed installation setup.
The power supply, transmitter and receiver amplifiers and the carrier frequency generators are located in Apparatus cabinet 1. The channel units (with call modulators and filter chains) and the call converters for three voice channels are located in the two apparatus cabinets 2 and 3, which have virtually the same structure. The corresponding measuring and testing measures with a tube voltmeter for checking the tubes and circuits are located at the top of each cabinet.
The speech channels are each transmitted in a sideband below six carrier frequencies:
Channel 1 | Channel 2 | Channel 3 | Channel 4 | Channel 5 | Channel 6 | |
Carrier frequency | 40 kHz | 45 kHz | 50 kHz | 55 kHz | 60 kHz | |
Modulation frequency | 300 - 3400 Hz | 300 - 3400 Hz | 300 - 3400 Hz | 300 - 3400 Hz | 300 - 3400 Hz | 300 - 3400 Hz |
Transmitted sideband | 36.6 - 39.7 kHz | 41.6 - 44.7 kHz | 46.6 - 49.7 kHz | 51.6 - 54.7 kHz | 56.6 - 59.7 kHz | 61.6 - 64.7 kHz |
To operate a TLD connection with a relay station, a ZT 11g relay amplifier must be connected in between to amplify the signal.
Technical principle
Multi-channel adaptor in frequency multiplex technology for the transmission of six speech or telegraphy channels.
Tube configuration
Development
The system was developed together with the SE-213 (TLD) by Brown Boveri in 1942/45 and only ordered in 1946 in the relatively small quantity of 22 sets of equipment at CHF 48'750.- each. Only a small pre-series of the HK-1/m microwave relay station, which would have been optimal to cooperate with the MK-2, was ordered.
Delivery of the sets was delayed until 1950 and the systems were liquidated around 1965.
Deployment
The sets were used in the Fk Kp and Fl Uem Kp on radio relay connections using the TLD. As they were quite cumbersome to transport and were only ordered in small quantities, the TLD was unable to make profit on its advanced technology and was only rarely used for point-to-point connections.