5kW DVB-T transmitters 2017-09-25T17:21:56+00:00

5kW DVB-T transmitters – Rai Way (Italian public broadcaster)

During Italian ATV switch-off in Puglia (a beautiful southern Italian region), Nexum installed a large DVB-T system based on 5 x 5 kW RF output power transmitters. Final Customer was Rai Way and transmitting site was known as Turrisi. TV transmitters were liquid cooled and manufactured by Plisch while the cavity combiner was supplied by COM-TECH. Heat dissipated by the transmitters was brought to the external mounted heat exchangers via a complex system of redundant stainless steel tubes. Also heat exchangers are redundant (5 + 1). Despite the time schedule was challenging, the system was commissioned on time avoiding any user’s disruption.

Project details

Plisch transmitters operated in active reserve configuration. Each transmitter is based over two separate amplifying sections (each one 2,5kW) which are internally combined. In case of fault of one of them, Spinner coaxial switch still put on air the operating one while the defective is switched off. In this way, in case of single fault, Rai Way MUXes remains on air with a RF loss of only 3dB.

Being a liquid cooled system, heat exchangers are a very important part of the transmitters. For this reason they are fully redundant, sheltered from the sun and protected from animals or unauthorized access.

At the ground floor, the pumps were installed. They keep moving the cooling liquid. Like all other parts of the transmitting system they are fully redundant.

All RF connections were made by coaxial rigid lines 1-5/8″ & 3″. Coaxial rigid line paths include tunable VSWR elbows, directional couplers & VSWR compensation adapters. All of them were fine tuned by Nexum’s technicians.

Another view of the complex network of stainless steel tubes between pumps and heat exchangers.

RF signals coming from the transmitters were combined trough a cavity filter system supplied by the Italian specialist COM-TECH.