MART TV broadcasting transmitters
Victor Model, Evgeniy Bykov

Mart Company comes from the Komintern All-Union research institute, the USSR parent enterprise engineering powerful TV and radio transmitters. Since 1994 the company has manufactured more than 2,000 transmitters broadcasting on the territory of 80 regions, from Kaliningrad to Petropavlovsk-Kamchatskiy.

During the last 8 years three transmitters' generations have changed, and the fourth one is being created now. At the first stage, in 1994-1996, transmitters had Soviet-times embodiment and were manufactured on the Soviet elemental base. In 1997-1999 the company started manufacturing transmitters with European 19" embodiment using output stages with bipolar Philips Semiconductors transistors, as well as other elements of the world leading manufacturers. In 1999-2001 the company migrated to MOS-FET and LD-MOS field transistors manufacturing. And finally, in 2001-2002 all transmitters migrated to surface-mounting technology with application of bulk of SMD elements.

Both TV and radio transmitters of all powers are designed according to the same principles. Each block has its own in-built feeding system and, if necessary, in-built cooling system. All transmitters' final stages employ powerful Philips Semiconductors field transistors characterized by high reliability, mismatch withstandability, high amplification, high amplification factor, and full reiteration of parameters. All transmitters have one-type set of amplifying modules, filters, coolers, demountable connectors, and power feeders. The power feeders have undergone considerable alteration in the scheme of rectifier diode reverse-direct switching, which allowed reducing the load of key-elements and improving reliability considerably. Components that showed blow reliability during their exploitation were removed from the transmitters' units and replaced with more reliable, though more expensive components. However the last generation's principal distinction is that, when designed, all transmitters were regarded as a component within one unified range that allows developing its consumer characteristics during long period. Thus, for instance, during 2002 the company is planning to integrate unified microprocessor management, and remote control and monitoring system into all transmitters. All stated above, along with the introduction of obligatory vibration resistance and temperature cycling testing, provides considerable improvement of the transmitters' reliability. This will bring new possibilities in gradual power growing, flexible reservation, and additional service.

TV-transmitters

Now MART manufactures only solid-state TV-transmitters of 1 W...5 kW.

New transmitters differ from the older ones in the following characteristics:

• mismatch withstandability: transmitters of up to 100 W may operate even in case of the transmitting line's break;
• high-quality parameters within all band (for DMW - 21...52 TV channels) are provided thanks to the usage of broadband amplifiers with no channel-dependable circulators;
• possibility of easy transmitters' tuning within the band thanks to the fact that exciters, power amplifiers and transmitters of 1 and 10 W are designed fully according to surface mounting technology.

New TV transmitters, as before, do not employ any correctors for providing the necessary TV-signal parameters. Quality of the parameters is achieved at the expense of exciter's high quality and necessary linearity and broadbandness of power amplifiers, which allows keeping output parameters of the transmitter during its proper operation without staff support.

MART TV transmitter

Transmitters of up to 2 kW are manufactured with common display and sound signal amplifier; transmitters of 5 kW use separate amplification.

Transmitters of 1 and 10 W are designed in bench-top version in a frame of 2U height, containing exciter and power amplifier. Other transmitters have two main blocks: exciter block and power amplifier block. Exciter block may contain an additional control demodulator or generator of TV test signals. Power amplifier block may have two amplifiers with output power of 100 W (PA-100) or two amplifiers with output power of 300 W (PA-300) in the common amplification mode and 400 W (PA-400) in the separate amplification mode.

Transmitters of 100 W without stand-by are designed in bench-top version. Other transmitters are rack-mountable.

All the transmitters of 200 W and more use parallel summation of amplifying modules. Transmitters of 200 and 500 W use 2 PAs, transmitters of 1 kW and 2 kW use 4 and 8 PAs respectively, and 5 kW transmitters use 16 PAs in display channel and 4 PAs in sound channel. Transmitters of up to 1 kW are manufactured both with automatic switching reserve amplifier and 100% stand-by. Transmitters of 2 and 5 kW do not require 100% stand-by and are manufactured with reserve amplifier only.

In 2002 MART company is planning to develop new series of solid-state transmitters of 5...20 kW with common amplification.

MART was the first company in Russia who developed and set into exploitation transmitters for DVB-T digital broadcasting. The transmitter of 500 W is operating in Nizhniy Novgorod, transmitters of 500 W and 1 k W are operating in Saint Petersburg. Transmitters employ modulators manufactured by the Tandberg company. Power amplifiers repeat all standards completely. In them the ratio between analog signal on-peak power with common amplification and average digital signal equals 6 dB is achieved, which complies with leading world manufactures' specifications. Having completed developing analog transmitters of up to 20 kW, MART is going to start delivering digital transmitters of up to 5 kW.

USW-FM transmitters

Since May 1999 MART JSC has been manufacturing series of Iney transistor transmitters of 30 W...4,0 kW within a common unified range.

Its peculiar properties are as follows:

• three types of main blocks: amplifier with various output power levels (which is also a transmitter of up to 250 W), 500 W and 1,000 W amplifiers;
• automatic limiting of power up to safe level in case of antenna match degradation, or if the environment temperature rises beyond acceptable exploitation bounds (e.g. continuous broadcasting);
• automatic start-up after voltage failure of any duration;
• all standard specifications for broadcasting signal in any operating modes and conditions (including antenna's functioning during any mismatch load) are observed;
• automatic interchangeability of transmitters by means of interconnection through the remote control ports without any additional devices involved is possible;
• minimal exploitation costs;
• full correspondence with requirements to output of new GOST P 51741-2001.

Three years of successful exploitation of this series prove high effectiveness of the accepted decisions that allowed creating transmitters with optimal relationship of performance specifications, exploitation reliability, and cost.

MART radio transmitter

Provided by MART Company.

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