RF systems
KNTV-TV moves to San Bruno Mountain
KNTV served the Salinas and Monterey, CA, markets for 45 years from Loma Prieta Mountain. In 2001 KNTV switched to covering the San Jose, San Francisco and Oakland DMA. In order to improve coverage, the station decided to move the transmitter location to San Bruno Mountain.
Although KNTVfs tower site was an existing facility on a mountaintop near the San Francisco airport, there were both FAA and environmental concerns due to the fact that the tower height was being increased by 57ft. It took three and a half years of planning, petitions, hearings and legal motions that added challenge, time and cost to this project.
Besides monitoring, there is only 30ft of analog signal path between the DA converters and the transmitter inputs. KNTVfs new transmitter site was designed to be as reliable as possible, with all systems configured as dual and most as hot standby. The Thales OPTIMUM solid-state VHF NTSC and DTV parallel transmitters satisfied this need. Liquid cooling offered the station two important benefits. The transmitter cabinets are physically smaller because there are no air plenums. It also helps reduce operating expenses because heat energy is transferred outside the building, minimizing the requirement for building cooling systems.
The transmitter facility was remodeled to the extreme with construction and project management services provided by McCormick Construction. The existing 35ft x 35ft cement block building was completely stripped before the new construction proceeded. A new roof, new electrical, new flooring, new HVAC, new security system and water storage systems completed the building upgrade. A total upgrade to current seismic code for both the building and the tower were completed. In addition, the existing tower was stripped, and the top 110ft was replaced with new steel before the new Dielectric antennas and transmission line were installed. A new grounding system was required to protect all the solid-state hardware from lightning strikes. SAE designed and installed a special grounding system that provides 5Ω to ground from anywhere on the site.
Emergency power for the sitefs entire load was installed, including a new UPS, automatic transfer switch, diesel generator and fuel storage system. GE provided a kinetic energy UPS system with sufficient capacity to keep KNTV on-air during any momentary power bumps or surges. The emergency power system is fully automatic with adequate fuel storage to keep the site on-air at full power for up to seven days.
Design TeamTechnology at Work Thales Broadcast & Multimedia: Thales OPTIMUM solid-state liquid-cooled transmitters Gordon Gummelt, control and electrical TDV216KOLV, TAV260KOLAS Henry Fries, electrical and RF Jean Labarre, control and electrical Bill Onyski, site layout design Todd Loney, commissioning eng. KNTV: Richard Swank Gensler, architect Massetti, MEP consultant McCormick, construction and mgmt. Rosendin Electric, electrical Seacomm Erectors, tower work
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