KUAT Deploys Comark 55 kW Parallax UHF DTV Transmitter

Arizona Public Media’s PBS member station KUAT Tucson, Ariz., is now on the air with a Hitachi Kokusai Electric Comark 55 kW Parallax UHF DTV transmitter.

KUAT’s former 20+-year-old primary IOT-based DTV transmitter on Mt. Bigelow sustained irreparable damage during winter storms and as a result the station was forced to run at half power via an FCC STA until a replacement could be acquired.  Earlier this year, Comark supplied, installed and proofed a new Parallax model HPTV-PRLX-U32 DTV transmitter to meet the customer’s 54.83 kW TPO requirement.

The new transmitter consists of two rack cabinets each equipped with 16 UHF power amplifiers. The Parallax transmitter has been delivered with dual Exact-V2 ATSC exciters (in main/standby configuration) and the liquid cooling system. In addition, Comark supplied the complete RF mask filter system that incorporates Constant Impedance Filter (CIF) technology and the high-power external hybrid’s for combining both of the transmitter’s PA cabinets.

Parallax provides a future-proof design to broadcasters:

  • High efficiency with wideband Doherty technology
  • Unique vertical high-gain power amplifiers, providing 2kW per PA module for UHF
  • Asymmetrical Doherty; provides same power in 8VSB (ATSC 1.0) and OFDM (3.0)
  • EXACT-V2 DualCast ATSC 1.0 / 3.0 upgradeable; preserves investment
  • Hot-swap AC to DC rectifiers with >96% efficiency
  • Made in the USA; serviced and supported out of Southwick, MA

Comark worked with the staff of KUAT to coordinate the shipment, offloading, and placement of the new equipment in the transmitter facility. Mechanical installation of the new transmitter system was completed by late May, followed by the turn on, where Comark performed the complete proof-of-performance testing.

“Comark worked very closely with the engineering management of KUAT to provide a complete solution for their site’s unique requirements,” said Joe Turbolski, Comark VP of sales and marketing. “Our program management performed a detailed site survey to ensure there were no surprises during the delivery and mechanical installation. And our field services group took special care to ensure the system was installed to provide trouble-free operation for years to come.”


Chris Homer, chief broadcast engineer for Arizona Public Media, said: “Our new 55 kW Parallax Transmitter has solid state liquid cooled design to meet our current ATSC 1.0 distribution across all of southern Arizona and is Next Gen (ATSC 3.0) ready for the future.”

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