Radio broadcasting transmitters of Technosystem and Screen Service Italia

By Nikolaj Kiselev

Review contents:

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5 kW STU-35 TV-transmitter of Technosystem is a solid-state transmitter, intended for TV-broadcasting (UHF, VHF).

The features of this transmitter are following: a modular assembly, a separate video and audio amplifying. The system architecture provides the simplicity of the mounting and maintenance, so practically each block can be is easy moved, checked or replaced. Depending on modulator the transmitter can work both in analog and in digital mode. If the digital modulator is mounted, the combiner “video-audio” will be simply unplugged. At an output the combiner “video-audio” is provided by means of balanced filter of CIN-architectures to unite the insulated video and audio channels exactly. The control block provides a transmitter full control without any personnel. The system is formed by central processor and peripherals, installed in each block of RF-amplifiers and in some other equipment subsystems. For convenience of data change between periphery and central controller the RS-485 protocol is used, which is supported by special software. As a result each switching or preparing of any command occupies not more than 200 ms. The system’s power supply is located in the power amplifier cabinet. Through nonadjustable and dubbed source of the direct current this system supplies all modules. Protection from casual voltage upsurges is provided by using of two independent transformers. The air cooling system the air is blown out through amplifier blocks by low noise and high reliable ventilators, located in the power amplifier cabinet and dubbed for reliability. These ventilators are controlled by a special circuit. The cooling system is built-in system at whole. The transmitter can work night and day at the temperature from 0 to +45°C.

The features of this transmitter are following:

• VHF and UHF ranges;
• Carrier stability is ±200 Hz/6 months;
• Input resistance (video channel) is 75 Ohm;
• Input resistance (audio channel) is 600 Ohm;
• G, D, K, I, M, N standards;
• Inter-modulation ≤ 60 dB;
• Accidental emission ≤ 1 mW;
• Modulation class C3F, F3E;
• Nonlinear distortion ≤ 0,5%;
• Nominal input level (±50 Hz) is from -10 to +6 dBm;
• Signal/noise ratio ≥ 48 dB;
• Total harmonic distortion ≤ 0,5%;
• Synchronous modulation AM ≤ 46 dB (referred to 100%);
• Power consumption ≤ 20 kW;
• Air forced cooling (3000 m3/h);
• Dimensions: 1168×1920×1200 mm.

The transmitter is certified by GCRF of communication and informatization. The certification system is “Electrical communication”.

10 kW TV-transmitter STU-41 of Technosystem company also is the solid-state transmitter, intended for TV-broadcasting (UHF, VHF), which has the analogous features as 5 kW STU-35 TV-transmitter.

The features of the STU-41 transmitter are following:

• VHF and UHF ranges;
• Carrier stability is 100 Hz/1 month;
• Input resistance (video channel) is 75 Ohm;
• Input resistance (audio channel) is 600 Ohm;
• G, K, I, M, N standards;
• Modulation class C3F, F3E;
• Inter-modulation of video and audio ≤ 70 dB;
• Accidental emission ≤ 1 mW;
• Total harmonic distortion ≤ 0,5%;
• Nonlinear distortion ≤ 5%;
• Signal/noise ratio ≥ 48 dB;
• Synchronous modulation AM ≤ 46 dB (referred to 100%);
• Power consumption ≤ 34 kW;
• Air forced cooling;
• Dimensions: 1624×1200×1920 mm.

The transmitter is certified by GCRF of communication and informatization. The certification system is “Electrical communication”.

20 kW TV-transmitter STU-42 of Technosystem company is solid-state, intended for TV-broadcasting (UHF, VHF). He also is module, with separate amplifying of video and audio and possibility of the analog modulator change by a digital modulator.

The features of this transmitter are following:

• VHF and UHF ranges;
• Carrier stability is ±200 Hz/1 month;
• Input resistance (video channel) is 75 Ohm;
• Input resistance (audio channel) is 600 Ohm;
• G, D, K, I, M, N standards;
• Inter-modulation of video and audio ≤ 60 dB;
• Accidental emission ≤ 1 mW;
• Modulation class C3F, F3E;
• Nonlinear distortion ≤ 5%;
• Signal/noise ratio ≥ 48 dB;
• Total harmonic distortion ≤ 0,5%;
• Synchronous modulation AM ≤ 46 dB (referred to 100%);
• Power consumption ≤ 70 kW;
• Air forced cooling;
• Dimensions: 1664×1915×1200 mm.

The transmitter is certified by GCRF of communication and informatization. The certification system is “Electrical communication”.

SCT transmitters of 5, 10 and 20 kW

The transmitters of SCT series from Screen Service Italia are used as low outputed transmitters, or as exciters. They differ by their modular forming. Video and audio amplifying can be as joint, so and separate. These transmitters are mostly used as exciters for the radio frequency amplifiers. For instance, in this area they are used in transmitters, about which is told above, but only with some revisions, or as low outputed transmitters with power from 2 to 10 W. The transmitters of SCT series consist of up converter and AM-modulator (SCS-320). Equipment of this series provides the high signal/noise ratio at signal transmission. From front panel it is the possibility of easy change. In this equipment the mode of exact CFO (the carrier frequency offset) is provided. The transmitters are provided by connector for sending of the external 5 MHz signal, as well as by a standard 25-pin connector of the RS-232 interface, to which it is possible to connect the modem in purpose of the remote monitoring realization.

It is possible the round-the-clock transmitter functioning at the temperature from -10 to +45°C.

The features of this transmitter are following:

• Output power is 2, 5 and 10 W;
• Output resistance 50 Ohm;
• Inter-modulation (-8, -10, -16 dB) < -64 dB;
• Output connector — N, jack;
• IF-connection with monitor — SMB;
• B, D, G, H, I, K, M, N standards;
• Accidental emission < -55 dB;
• Working frequency ranges: UHF IV and V, VHF I and III;
• Maximum humidity 90%;
• Power supply 115/230 V ±20%;
• Power consumption: 60, 90 and 170 VA, depending on output power;
• Dimensions 3U.

The transmitter is certified by GCRF of communication and informatization. The certification system is “Electrical communication”.

Material is provided by the “Broadcast Arsenal XXI” group of companies