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RF systems

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Grass Valley

KWHY-TV is an NBC owned-and-operated Spanish-language station serving the Los Angeles Hispanic market. The station's analog channel 22 and digital channel 42 have been co-located since 1999 at the Mt. Wilson RF complex.

The present transmitter building will be vacated at the end of analog television. The KWHY-DT facility has been operating at 86kW ERP. However, RF studies determined that the ERP could be increased to 486kW. The studies also showed that coverage of the Hispanic community could be enhanced for the digital age by relocating to neighboring Mt. Harvard and sharing a transmitter room with sister station KVEA-TV Telemundo on analog channel 52.

Mt. Harvard is accessible only by four-wheel drive vehicle. Electricity rates in Southern California are among the highest in the nation. For these reasons, KWHY determined that reliability and efficiency were prime design factors for the replacement transmitter. Having evaluated the options, the design team selected the Grass Valley DCX Paragon digital transmitter, using up-to-date MSDC IOT technology.

KWHY already used a Grass Valley DCX transmitter for its digital service from Mt. Wilson, and the team considered moving it to the new location. However, it came up with a more imaginative solution. The existing DCX transmitter at Mt. Wilson was converted to an IOX analog transmitter by swapping out the exciter and modifying the RF system. This gave the station a newer, more reliable analog transmitter, retaining the existing one as a full-power backup. New DCX Paragons were installed at Mt. Harvard for the digital channel.

A single DCX Paragon amplifier cabinet is capable of providing the required KWHY TPO of 19.5kW. A second DCX Paragon cabinet was installed as a standby. This particular configuration, using MSDC IOT technology, maximized electrical savings and allowed KWHY to qualify for a substantial business incentive rebate from Southern California Edison, which helped offset the capital expenditures of the equipment.

A Dielectric TFU-26GTH slotted-coaxial antenna with 1.6° of electrical beam tilt and 0.6° of mechanical beam tilt was selected to optimize coverage of the Los Angeles metropolitan area, mounted on an existing 100ft tower. Tower work was performed by Stainless and Sunray Services. KWHY-DT went on the air from Mt. Harvard on June 28, 2006.