WEWS-DT - TvTechnology

WEWS-DT

WEWS-DT received construction permit approval for a power increase to 870KW and ordered their 50KW average power Visionary DT series transmitter from Axcera in November 2001 for a January 2002 delivery.
Author:
Publish date:

WEWS-DT is one of 10 television stations owned and operated by the E.W. Scripps Company. Early in the DTV transition, Scripps made a decision to convert all of its stations to full-power digital as quickly as possible. Thanks to the Scripps Corporate commitment, WEWS-DT began operation on Sept. 4, 1999, despite the fact that the station was not required by the FCC to begin operation until Nov. 1 of the same year. The goal was to be an aggressive market leader and a flagship affiliate in digital television by airing all the ABC “Monday Night Football” games in HDTV in the 1999-2000 season.

At NAB2000 an ad-hoc committee of Scripps engineering managers reviewed the state-of-the-art transmitter offerings for future group purchases. After a detailed review of all major manufacturers, a consensus determined that Axcera had the most to offer in an expanding digital television market.

WEWS-DT received construction permit approval for a power increase to 870KW and ordered their 50KW average power Visionary DT series transmitter from Axcera in November 2001 for a January 2002 delivery. They also requested an authorization from the FCC to take WEWS-DT off the air for up to 30 days during the conversion. In order to minimize the off-air time of their digital signal, they began removal of the existing transmitter system to prepare for the arrival of the new system. There was a substantial amount of work required to complete the conversion.

Since the previous DTV transmitter was a single tube unit, the output RF system was simple. However, in order to achieve their full licensed power, it was necessary to install a dual-tube transmitter with a large waveguide system to combine the output of both tubes. As a result, it was necessary to reinforce the ceiling of the transmitter room in order to support the additional weight of the combiner system. To achieve this, they added a rolled-steel beam to the ceiling along with large steel plates to distribute the weight across the ceiling.

Additionally, with ceiling space constraints they were not able to hang a standard combiner/filter combination horizontally, so Axcera took advantage of the ceiling height and provided an e-plane RF system to meet this challenge. This type of RF system is configured vertically, rather than the more typical h-plane or horizontally configured system, so it worked well for their application.

Once the room was prepared, the Axcera service team began installation of the new transmitter system, which was on the air at full licensed power by March 1, 2002.

WEWS-DT was fortunate to have received digital allocation of Channel 15 as it is low in the UHF band and, therefore, provides the best coverage. Additionally, since it is not the lowest channel in the band, lower-sideband interference issues that plague Channel 14 allocations are avoided. The digital coverage is excellent, well beyond the five county areas covered by their analog signal.

The 50KW Axcera transmitter and the slotted UHF antenna at 800 feet on the tower perform exceptionally. They have received signal reports from as far away as Delaware County, OH, to the south and Toronto, Canada, to the north.

Design Team

WEWS-DT:
John Workman, director of engineering
Jim Baird, engineering manager
Ric Harris, general manager
Mike Doback, Scripps corporate director of engineering

Axcera:
Don “Maxx” Thomas, Sr., field service engineer
Kevin Wible, test engineer
Jeff Heldman, applications engineer
Paul Grzebik, regional sales manager

Previous page | Next page