Riz

RIZ transmitters are manufactured in Croatia and RIZ are one of the only SW transmitter manufacturers in the world making
high power transmitters for the 3 to 30 MHz bands. As well as conventional AM transmitters RIZ also produce DRM transmitters.

A typical 50KW transmitter is the 50 kW SW BROADCASTING TRANSMITTER TYPE RIZ OR 50 K-01/A

BASIC CHARACTERISTICS AND USES

RIZ Short Wave Broadcasting Transmitter type RIZ 50 K-01/A is an automatic tunable amplitude modulated transmitter, capable to operate at any frequency within 3.2 and 26.1 MHz frequency range, with carrier power of 50 kW.

Using Pulse Duration Modulation (PDM) the transmitter provides higher efficiency, lower operating costs and overall performance superior to that of any other standard SW transmitter in the 50 kilowatt power range.

It meets all CCIR requirements for this type of service.

The transmitter itself is constructed as a self-contained unit.
It consists of four cabinets designed as rolled-in units. Therefore, it is very suitable for installation in containers for fixed or mobile stations.

All control and monitoring elements are concentrated on the front panel of the transmitter. The transmitter supervision is facilitated by the use of display indicating the equipment status.

FEATURES

The 50 kW SW Broadcasting Transmitter type OR 50 K-01/A has the following major characteristics:

• Pulse Duration Modulation
• application of up-to-date technology
• the most modern high efficiency tubes
• convenient and simplified installation
• easy front and rear access
• minimised exploitation and maintenance costs
• reliable operation in extreme climatic and environmental conditions
• automatic tuning
• possibility of remote control and unattended operation.

CIRCUIT DESCRIPTION

The transmitter consists basically of four sections, as follows:
AF Chain, RF Chain, Rectifiers and Automatics.

RF CHAIN
The RF chain is conventional, using only two tubes:
one in the RF3 final stage and one in the RF2 driver stage, while the RF1 stage is fully transistorized.

The newest type of tube, tetrode RS 2054 SK with graphite grids structure cooled by the vapour condensation, is used in this stage
as a Class C power amplifier.

Output power is via coupling capacitor and double P1-filter transferred from the tube plate to the coaxial output of the transmitter. Necessary attenuation of harmonics is achieved by passing via harmonic filter.

TUNING AUTOMATICS

After the setting of the required transmitter operating frequency on the synthesizer, the automatic transmitter tuning system
allows automatic tuning of the transmitter final power stage to required frequency.

OPERATING CHARACTERISTICS

The transmitter is designed for continuous 24-hour operation with an average modulation depth of approximately 60% and peaks up to m=100%.

Over modulation
The transmitter can withstand, without damage, a short duration of AF input signals fm=1 kHz, 6 dB above the level required for 100% modulation.

24-Hour Test Operation
The transmitter is designed for 24-hour test operation as follows:
100% modulation depth with a sinusoidal signal, frequency 1 kHz, for duration of 10 minutes, after that, with 60% of average programme modulation depth for a duration of 50 minutes, and so on within 24 hours.

Stability of Technical Data
The technical data stated in this specification are guaranteed for mains voltage tolerance between +5% to -10%, with the exception of RF output power, consumed power, efficiency, and carrier shift.

TECHNICAL SPECIFICATIONS