Sets of channel amplifiers

Modern technology and well-proven design - channel amplifiers of ZG series from Alcad. Long-standing presence in European markets enabled the devices to gain brand recognition among designers and installers of MATV/SMATV systems. These channel amplifiers allow to perfectly distribute analog and digital signals. Due to their high selectivity, they are ideal devices both in the transition period and after the analog switch-off, in the totally digital era of DVB-T television. The article describes applications of ZG family.

View of the set consisting of SP-126 R912120 frame, AS-125 R90508 power supply, 1x ZG-201 R90512 amplifier, 9x ZG-601 R90538 amplifier, and CO-405 R905079 channel converter

Main advantages of the sets based on channel amplifiers of ZG-series:

The series comprises many kinds of channel amplifiers with different parameters and able to work in many countries (prepared for different TV systems). As an example, in some central European countries (including Poland) there may be used:

The amplifiers are powered from the AS-125 R905083 power supply and mounted in the SP-126 R912120 frame (maximum capacity of the frame - 12 ZG modules).

If the set of amplifiers is to be installed in a server room, it should be placed in the SP-725 R912037 frame suitable for RACK cabinets (the frame is capable of housing up to 9 ZG amplifiers).

ZG sets are characterized by high noise immunity, i.e. they can work (the amplifiers and power supply) even in environments with comparatively high level of electromagnetic disturbances, without noticeable impact on quality of the output signals. It has been reached due to solid metal construction, good shielding of active and passive elements, and special design of the power supply.

Maximum unevenness of gain (it has been proved experimentally) within any channel (there have been tested many amplifiers for different channels) is from -0.5 dB to +0.3 dB (the requirement: +/-1.5 dB). Any channel amplifier of the series is characterized by high stability of its gain, frequency characteristics and other parameters in changeable conditions (e.g. fluctuations of supplying voltage or working temperature).

The great advantage of ZG-401 series is high selectivity, consisting in capability of filtering the wanted signal from among the variety of signals on the input. Attenuation of undesirable signals on N+2 channel equals 37 dB, and on N+3 channel is 60 dB.

ZG-421 amplifiers have even greater selectivity. They can be used in situations when TV signals are received in adjacent channels and one of the channels should be amplified (e.g. one of two signals from transmitters broadcasting on adjacent channels). In such a case, the high selectivity of the ZG-421 amplifier will allow to strengthen the desired channel, provided that the level of the unwanted adjacent channel is not higher than the level of the useful signal.

The important parameter of an amplifier is noise figure, being the indicator of its quality. The first stage of amplification is crucial for the whole antenna installation and the resultant noise parameters. The noise factor of the amplifiers with maximum gain is at the level of 3.5 dB (the permissible level is 8 dB).

Nonlinear distortions caused by nonlinear characteristics of active elements are practically eliminated due to proper design and use of best components and they do not affect operation of the amplifier sets. The margin of intermodulation products of the third order (measured with 3-signal channel method) equals to 68 +/-1 dB (the required min. value is 54 dB).

The maximum output level (with maximum 53 dB gain) is 123.5 dBuV, which is a very good result.

The full set includes the SP-126 R912120 mounting frame (with optional CP-126 R905124 box) and AS-125 R905083 power supply (see specifications in the second table).

ZG family of Alcad complies to ISO 9001 (ER-196/1/96) requirements and features high operational reliability. The chosen set of amplifiers and the power supply are mounted on the frame made of ZN-AL alloy, which allows for easy assembling and ensures good common grounding.

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