DENVER—Rocky Mountain Public Media (RMPM) is working on a network-wide project to upgrade multiple transmitter sites and build the Buell Media Center, a new downtown facility that will integrate master control and production facilities for two flagship media properties.
These properties include KRMA-DT, a 1,000 kW ERP TV station serving the Denver market. KRMA was designated as a “Phase 2” repack station, relocating from UHF Channel 18 to 33. The frequency change required an entirely new transmission system, including a new transmitter, filter, and antenna at the KRMA transmission site on Mt. Morrison.
The station’s long-running Harris Sigma tube transmitter had been in service for many years, and the repack presented an opportunity to transition to modern, solid-state technology. That transition, which included a GatesAir Maxiva ULXTE liquid-cooled transmitter, introduced higher operating efficiencies and addressed rising concerns around tube maintenance and replacement.
We selected the ULXTE-50 for one main and two subchannels at 26 kW TPO. The transmitter includes additional headroom for potential future services, including NextGen TV. The ULXTE provides immediate return value for operations, including a redundant closed-loop pump system to transfer heat to outdoor exchangers.
The advantage of the closed-loop design over the single-pump, open-loop system of the tube transmitter is that it provides a more sophisticated platform to monitor the pump system, including temperatures, evaporators and general operating status. One recent example includes troubleshooting a water flow problem that originated from a failing flow meter. The ability to remotely connect to the transmitter, monitor parameters and troubleshoot issues leads to quick resolutions.
These modern efficiencies extend to power density, energy consumption and maintenance. The ULXTE packs more power density and redundant technology into the cabinet. While solid-state transmitters can produce more heat than tubes, the ULXTE’s efficient use of liquid cooling maintains a consistent operating temperature even at very high power.
A NEW LANDSCAPE
Migrating from a single-tube system to a redundant solid-state system completely changes the maintenance landscape. The ULXTE architecture leverages redundant, hot-swappable power supplies and amplifier modules. If one fails, the transmitter continues to operate at near full power, and replacement is a matter of unscrewing and pulling out the module before inserting a new one.
Few parts are required to maintain these transmitters. GatesAir ULXTE air-cooled transmitters have since been installed at RMPM sites in Fort Collins, Grand Junction, Montrose and several rural communities, as well as a July 2020 planned replacement in Durango. A common set of spare parts can be shared across the entire network of transmitters, which keeps costs low and makes life easier for the single RF engineer that maintains these sites. One of these ULXTE transmitters is also installed at the Mt. Morrison site providing backup service for KRMA.
The ULXTE also offers native IP connectivity. The Buell Media Center buildout includes a new 100 MB/s IP microwave and fiber system to transport broadcast content over 16 miles to Mt. Morrison. The integrated Maxiva XTE exciter provides an IP and ASI input to feed the transmitter, which allows for a native IP signal out of an encoder from the Buell Media Center. The XTE’s ASI connection takes in a feed from RMPM’s older studio location over a traditional microwave link.
GatesAir’s technical support teams provided exceptional service from start to finish. The system was so well-prepared in advance that their technicians weren’t required to be onsite on cut-over day. KRMA was able to meet its repack deadline without delay, and went to air from the new transmitter without technical difficulties.
Doug Houston can be reached at DougHouston@rmpbs.org.
For more information on GatesAir, visit www.gatesair.com or please call Keith Adams at 513-459-3447.
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