A Foundation for the Future
Mar 1, 2007 12:00 PM, By Keith Stuhlmann
Ft. Myers Broadcast Company, a privately-held, family-owned broadcast business nestled in southwest Florida since 1940, and who established the first radio and TV stations in the market, recently put the finishing touches on a new transmission facility for its WINK-FM and WINK-DT stations serving the Ft. Myers -Naples market. In its most basic description, the project entailed the addition of a 40 feet by 60 feet space attached to an older, steel-framed transmission facility that still houses the WINK-TV analog and backup FM transmitters. But the story extends far beyond the basics into a highly complex project that begins at the base of a new cement building and rises to the top of a combined radio/TV tower 1,500 feet in the air.
A view of the old building with the new 40'x60' wing.
The new Harris transmitter.
The Caterpillar 3412 diesel-power generator serves as backup for the new wing.
Part of the power distribution system.
The coaxial cable access point to the outside.
The multi-year project began in September 2002 with a series of FCC filings that would ultimately preserve WINK-FM's full Class C status. Another regional station's request to increase power, if passed, would have reduced WINK's status to Class C-0. This would have made the station unlistenable near Marco Island, an Arbitron diary-keeping area that is financially important to the company.
Our June 2003 filing to preserve the station's Class C status eventually prevailed. The rulings would be central to a series of new antenna installations, older antenna modifications and choice of transmitters for the new transmission facility. Harris and Dielectric provided the new transmitters and antennas that have ultimately shaped the way we broadcast today and into the future.
The FCC has revised the Class C definition over the years. Originally, it was defined as a 100kW FM radiated at a height above 1,000 feet. The last revision requires that to preserve Class C status, the station must have a center of radiation at or near 1,500 feet. A lowered antenna position would place the station in the new Class C-0 status, reducing the station's protected coverage range. This means that fringe area listeners may lose the station's signal due to increased coverage from an adjacent or co-channel signal in a different location.
WINK's co-located TV operation proved advantageous over the course of the decision process. The TV/FM tower, standing at 1,519 feet, offered plenty of room and flexibility to implement unique antenna design strategies. We plotted the installation of a special stacked antenna directly after our 2003 filing. This would boost our FM center of radiation to 1,500 feet and also accommodate WINK-TV's DTV antenna.
The work on the new transmission facility was postponed when Hurricane Charley roared through the area in August 2004. Although our facility suffered no structural damage, the storm devastated homes and businesses in the southern part of Charlotte County, just north of Ft. Myers. Construction was halted as contractors worked to rebuild, so we turned our attention to building our HDTV studios and technical core.
Construction of the transmission facility was reinitiated as contractors again became available. Nu-Cape Construction of Cape Coral, FL, and Christopher J. Lee Architects of Ft. Myers assisted with facility construction and design. The new section of the transmission facility is essentially a giant bomb shelter; a 40 by 60 bunker-style cement block with a poured cement roof. The result is a completely hurricane-proof construction encompassing enough electrical, ac and transmission redundancy to ensure that all broadcast properties on site will remain on-air at all times outside of complete devastation.
Plans for accommodating the appropriate antenna systems for WINK-FM, WINK-TV, WINK-DT and future transmissions (such as HD Radio) remained consistent throughout the weather-related construction delays. These plans were set into motion as construction moved forward.
Antenna installations and modifications were complex and versatile: first, the installation of a stacked antenna designed by Dielectric consisting of a TDM-5FM antenna on top with a TW-6B9 TV antenna on the bottom. This accommodated WINK-DT terrestrial Channel 9 while preserving the Class C status for WINK-FM.
Second, a new eight-bay side-mounted Dielectric antenna was installed for WINK-TV terrestrial Channel 11. This antenna, a broadband system covering Channels 9 through 11, will automatically become the backup DTV antenna when the FCC-mandated analog TV shut-off date arrives on Feb. 17, 2009.
The old top-mounted Channel 11 antenna was removed, and the 10-bay ERI rototiller antenna that previously sidemounted near the top of the tower was lowered 100 feet and retained as a backup for WINK-FM. This antenna was lowered to its new position to remove it from the aperture of the new side-mounted Channel 9-11 TV antenna.
The new Dielectric antenna had a significant effect on our choice of FM transmitter. The older 10-bay antenna, with its high antenna gain, required only 25.5kW of transmitter power output. Dielectric's stacked, five-bay design prevented us from exceeding the FAA's ceiling height of 1,519 feet. It also changed our transmitter output requirement to 54.2kW because at only five bays the antenna gain was reduced. This led to our choice of a Harris HTD-60CD FM transmitter as the new main WINK-FM transmitter.
Ft. Myers Broadcasting has been a Harris transmission customer for TV and radio for a long time. The previous main WINK-FM transmitter, a Harris HT-25CD, is now in backup mode transmitting over the ERI antenna. (WINK-FM's previous backup, a Continental Electronics transmitter, remains installed in the older transmission facility with the HT-25 and several NEC and Harris TV transmitters for analog Channel 11.) WINK-DT recently went on the air with a Harris Platinum PTCD20P2 solid-state digital VHF transmitter in the new transmission facility. Meanwhile, several other regional Ft. Myers Broadcasting and Meridian Broadcasting properties � all engineered by Ft. Myers Broadcasting under a joint agreement � operate Harris FM and AM transmitters.
The HTD-60CD is effectively two 30kW transmitters running in parallel into a Harris-engineered switchless combiner. Dual exciter designs are incorporated into each side of the transmitter. The main exciter drives each transmitter with automatic switchover to the backup to continue operating at the same power in the event of failure or maintenance. The same design was used in the Platinum DTV transmitter via the Harris Apex digital ATSC exciter. The Harris Digit CD is used for all of our analog Harris transmitters.
The tube design of the HTD-60 is the same as most of our older Harris transmitters. The HTD-60 maintains much of the same cavity design as its older siblings, but uses an improved power supply, drawing less electrical current and offering a more stable product overall. The Pas and IPAs remain singular to each transmitter, which allows us to take one offline and remain on the air with relatively strong signal coverage throughout the area. The HTD-60 also gets high marks for providing several monitoring points for standard remote controls, and offering a wide array of status readings for control and monitoring.
The switchless combiner, responsible for forwarding power from both transmitters into the transmission line and RF system, ensures that the station drops to only half-power if a transmitter is taken down for maintenance or other reasons. Without the combiner, the output drops to quarter-power. The drop to half-power means that only fringe-area listeners are affected. The HT-25 can provide close to full regional coverage in drastic situations, even though the ERI antenna is now positioned lower on the tower.
A Foundation for the Future
Mar 1, 2007 12:00 PM, By Keith Stuhlmann
A rear view of the support racks for the WINK-FM and WINK-DT transmitters.
The combiner network combines the output of the two 30kW transmitters to produce the 60kW output.
An overhead view of the HTD60 FM transmitter
The multiple changes and modifications to the tower between antennas and transmission line required a significant amount of tower strengthening prior to installation. Tower Innovations engineered the tower strengthening project, which required heavier cross members in certain areas and additional plates on older cross members to support the weight of the new and old antennas and associated transmission line. Tower Innovations provided the cross members and plates, with Dielectric providing the transmission line.
The new portion of the transmission facility spans about two stories from floor to ceiling. This left plenty of space above the transmitters for the line to shoot up and across the ceiling to the exit port, where it continues outside and to the tower bridge. A 6?" transmission line was used to handle the 54kW TPO for the WINK-FM transmitter, along with 3?" line for DTV transmission. This added quite a bit of weight to the existing 6?" analog TV line and 3?" FM line for the HT-25 transmitter.
While built as a standalone entity, the new transmission facility, is separated by a double door entry that allows engineers to move between the new and old rooms. With no room to squeeze a new transmitter, the 2009 shut-off date for analog TV means that all main transmission systems will operate out of the new section. To further emphasize the separate entity feel, each side features its own electrical system, cooling system, transformer and generator.
The original part of the transmitter site uses a diesel-powered generator for backup that came in handy for Hurricane Charley. The new side adds a giant UPS for the new WINK-DT and FM transmitters. A second diesel power generator was installed in February 2007; the HT-25 can also be switched on using the older diesel generator if necessary.
This area is cooled through two redundant Liebert ac units that operate on weekly alternating cycles to preserve the life of the units. One unit can handle the heat loads from the DTV and FM transmitters. A large, mounted exhaust fan and two air louvers were incorporated into the building design in the event of total ac failure. The fan automatically starts if the temperature climbs above the set degree, and the louvers automatically open to exhaust heat from the room and keep the transmitters in operating condition. The room normally operates as a closed system.
This additional failsafe cooling procedure was added due to an experience at another transmission facility that had a total ac failure from the Hurricane Charley power outage. The temperature in the transmitter room exceeded 130� on the engineer's arrival, and the transmitters shut down as a result of the heat. Similarly, four by four glass blocks were incorporated into the design. These blocks line the ceiling and walls, and allow engineers to work by sunlight rather than flashlight in the event of power failure.
The electrical system is designed so everything comes into the new side of the building at 480V and is then stepped down to address various electrical requirements. The transmitters run on less but the tower elevator requires the higher voltage. This also provides extra capacity for WINK-FM's future HD Radio transmitter, which will require a separate antenna. Electrical and floor space is also mapped out for a second DTV transmitter when the current Platinum transmitter moves to backup status. These considerations ensure that we'll never run out of electrical capacity or real estate for future transmission and RF systems for antennas.
The facility also is designed to remain clean, as it does not take in any outside air. The closed ac system eliminates bugs and debris. This all adds up to easier transmitter maintenance. The Harris transmitters require limited maintenance; keeping filters clean of dirt and dust, and paying attention to temperature and discoloration in the wiring jackets are the big issues. The HTD-60 allows us to take down one 30kW transmitter, inspect and clean it, and put it back online before repeating the same steps with the second transmitter. This is far easier than the hard switchover of the older transmitters (for which we also run weekly test loads for maintenance purposes).
Transmitter rack equipment is limited mostly to modulation monitoring, with units provided by Inovonics. An ATI distribution amplifier splits the signal to ensure it feeds the HT-25 in the older building. As we prepare for HD Radio, STL upgrades and additional monitoring and processing equipment will certainly be needed. For now, four years of FCC filings, antenna adjustments, tower strengthening and RF design work has paid off nicely. The new DTV transmitter went on the air on May 30, 2006, with the WINK-FM HTD-60 transmitter following on July 17 � with plans in place for future expansion.
Stuhlmann is the director of engineering of Ft. Myers Broadcasting Company and Meridian Broadcasting, Ft. Myers, FL.
- Amco equipment racks
- APC Silicon SL320KG UPS
- ATI distribution amplifiers
- Belden wiring and cabling
- Caterpillar 3412
- Dielectric stacked FM/DTV antenna (TDM-5FM antenna on top/TW-6B9 TV antenna on bottom)
- Dielectric transmission line
- ERI Rototiller antenna, tower
- Harris HTD60 transmitter, Digit CD, switchless combiner
- Inovonics modulation monitors
- Liebert ac units
- Moseley Starlink STL
- Orban 9300 audio processors
- Tower Innovations crossbars and plates