HIGH POINT, N.C.—While channel relocation is the primary reason behind purchasing a new transmission system for the spectrum repack, most broadcasters are also evaluating other aspects of their transmission operations. These include short-term paybacks related to efficiency and maintenance, and future opportunities associated with ATSC 3.0.
All of these elements affected our decisions at WGHP-TV, the Fox affiliate serving Greensboro, High Point, and Winston-Salem, N.C. As we evaluated transmitter options and repack-related services, all signs pointed to GatesAir. Installed and commissioned at the end of 2016, we have experienced near-immediate operational benefits and feel well-prepared to switch over to our new channel assignment.
LIQUID-COOLED
We wanted a solid-state transmitter to replace our two-tube IOT transmitter. GatesAir’s Maxiva ULXT liquid-cooled UHF transmitter offered the best balance between power level—we needed 54kW to make our 1 MW power rating—and RF efficiency. We now achieve 36 percent efficiency compared to the tube transmitter’s 23 percent.
WGHP-TV replaced its previous two-tube IOT transmitter with GatesAir’s Maxiva ULXT liquid-cooled UHF transmitter.
We opted for liquid-cooled over air-cooled for several reasons, mostly to minimize cooling requirements and utility costs at high power. The ULXT includes a liquid-to-heat exchanger that moves heat to the outside, reducing our heat load and lessening the impact on air conditioning. We’ve noticed an average of 20 Psi pressure vs. the 95 Psi with the old system, with a roughly 25 gallon-per-minute flow, running at about 90 degrees. The average flow before was about 88 gallons-per-minute.
The internal design provides easy access to all 10 modules, plus an IPA module in each power block. Each module has its own individual power supply; if one fails, there is no noticeable effect on the transmitter’s operation. Each module and power supply is hot-swappable—the power supplies are easily attainable—so replacement doesn’t require powering down.
We can access the power blocks, which take in the RF signal, through a back door in the cabinet. It is a simple arrangement and easy to move around, with no high voltage concerns outside of the 208 three-phase electricity hoses coming into the transmitter.
CHANGE FOR THE BETTER
We had to get used to a lack of front panel metering we had on the tube transmitter, however, we quickly realized GatesAir’s approach let us dig deeper. The webpage-based GUI can recall specific temperatures on any individual module, for example, and attain readings for temperature, water flow, voltage, current and other parameters that would normally require using a separate meter. With the ULXT, we have access to these readings from any connected location, and built-in e-mail will warn us if something goes awry before we notice.
The built-in Maxiva XTE exciter, which is ATSC 3.0-ready for the future, plays a substantial role in signal quality and compliance. We noticed a significant improvement in signal-to-noise ratio, safely landing in the 35-36 range and occasionally as high as 38 and viewers report fewer dropouts. As we see more cord-cutting on the fringes of our coverage area, we’ve also heard reports of improved reception with indoor antennas. The XTE’s integrated real-time adaptive correction (RTAC) software gives us direct visibility into signal compliance with precise signal measurements, ensuring we remain within the shoulder.
As we look toward repack, we are confident this transmitter will simplify our expected channel relocation. With the transmitters’ broadband design, a frequency change can be done mostly through the GUI, along with updated power meter calibrations to ensure the proper RF for the new channel. Now, we just await the word on what that channel will be.
Charlie Layno can be reached atCharles.Layno@wghp.com.
For more information on GatesAir, please visitwww.gatesair.comor call513-459-3447.
To follow our online coverage, visit our repack silo, www.tvtechnology.com/repack.
