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WGBH Upgrades Transmitter System

Comark
(Image credit: Comark)

SOUTHWICK, Mass.—Hitachi Kokusai Electric Comark has announced that the WGBH has upgraded it VHF Band 1 Parallax liquid cooled DTV transmitter for up to 47.8kW of power.

Comark supplied the Parallax transmitter on channel D5 to public media producer GBH as part of the FCC repack. 

This transmitter system was purchased in 2018 as upgradable to allow for future power increases and initially delivered as a three-cabinet system with four power amplifiers (PA’s) per cabinet (12 total) for operation at 6.2kW transmitter output power (TPO).  

After a few years, GBH applied for and received authorization from the FCC to increase the station’s ERP from 6.7kW to 34kW to better serve their community of license. 

GBH then ordered the system upgrade package from Comark that included 24 additional amplifiers and the associated materials, providing TPO capability of up to 47.8kW.  The new configuration of the GBH transmitter now uses 12 PA’s per cabinet or 36 PA’s total. 

“When we originally ordered the Comark Parallax transmitter, our FCC engineering consultant informed us that there was a strong possibility we could be granted a future increase in effective radiated power up to 50Kw,” said GBH transmitter supervisor Jon Frank in a statement. “However, we had no idea precisely what that increased power figure would be. As result, we purchased the upgradeable cabinet option with our original transmitter.  When we were granted a 34 Kw ERP, Comark's modular transmitter design allowed us to easily increase the transmitter’s power output in the field and to purchase only as many amplifier modules and combiners as we required.”

“Planning is the key. We had a lot of very detailed customer discussions during the initial phases of this system,” explained Joe Turbolski, VP of sales and marketing at Comark. “GBH had a long-term plan for their post repack D5 allocation for this transmitter system.  With Parallax, we were able to offer both the technology and the architecture that GBH required to make this project successful.”