Originally featured on BroadcastEngineering.com
4/21/2009 9:35 AM
Recent advances in LDMOS device power density and performance have contributed to significant improvements in UHF power amplifier linearity, efficiency and reliability. Based on this technology,
has developed a solid-state transmitter that allows OTA broadcasters to transmit an array of local, over-the-air broadcast services at various power levels. The transmitter’s architecture leverages new advances in LDMOS technology and other design initiatives to provide a range of benefits including more efficient and cost-effective operation at any power level. The new transmitter design is available in both liquid and air-cooled versions.
The transmitter platform operates from about 10W to more than 20kW average power. The power smart architecture lowers operating costs through improved efficiency and green design.
The Maxiva transmitter uses a 50V UHF LDMOS design, which results in an improvement in power per device and linearity/efficiency. The 50V devices are rated at 450W (CW) power per package.
Another important feature of the new 50V LDMOS devices is that the gain of each device is about 19dB, a large boost over standard 32V designs. This increased gain reduces the number of driver stages required, with power amplification handled in a single device as opposed to using a series of lower power RF devices for staged amplification.
The low-power UAX transmitters use the same RF pallets as higher power transmitters, but the pallets are mounted instead on a standard heat sink and cooled by fans providing clean filtered air. The result is a highly efficient design requiring fewer modules.
The architecture also enables a simple analog-to-digital upgrade path for international broadcasters through the use of Harris Apex exciter technology. All ULX transmitters integrate the Apex M2X exciter — a software-definable platform that enables analog broadcasters to easily transition to digital in the field and enables multichannel broadcasting of HDTV, DTV and mobile TV channels.
Check out this versatile transmitter in the Harris booth.