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December 18-25, 2003

The John Hancock Center, Chicago

It's always easy to spot a transmitter buff walking around downtown Chicago - they're the ones looking up at the two huge skyscrapers that are home to nearly all the Windy City's FM and TV facilities.

The Sears Tower, at 1454', is the tallest building in Chicago (and anywhere in the U.S., for that matter), but I've always found the John Hancock Center more interesting, for some reason.

Construction at 875 N. Michigan Avenue began in 1966, and the building opened in 1970. Its two rooftop masts rose 328' above the top of the building, itself at 1127', and soon became home to many of Chicago's TV and FM broadcasters, seeking higher perches than their existing downtown rooftop locations. (WBBM-TV 2 moved from 33 N. LaSalle Street, WMAQ-TV 5 from the Kemper Building it had called home since the late forties, WGN-TV 9 from the One Prudential building where its old mast still stands, and WFLD-TV 32 from Marina City, where WLS-TV 7 would remain until the construction of the Sears Tower a few years later. Thanks to Michael Disandro for filling us in on some of the historic transmitter sites!)

When I photographed the Hancock as a teenager in 1986, the key tenants on the west tower (seen at left in both photos at the top of the page) were WFLD (Channel 32), at the top of the mast, and WGN-TV (Channel 9), in the slightly wider radome below WFLD, with NBC's WMAQ-TV (Channel 5) below it, then religious independent WCFC (Channel 38) and a channel 2 backup below that. And below that was the Alford master FM antenna that was then the major FM facility on Hancock. The east tower's top was crowned by Spanish independent WSNS (Channel 44), which had offices in a lower floor of the Hancock, with CBS' WBBM-TV (Channel 2) just below. And below that were the Chicago City Colleges station, WYCC (Channel 20), WXRT (93.1) and independent WGBO-TV (Channel 66).

Seventeen years after snapping that picture from street level back in 1986, I finally found my way to the roof of the Hancock in early November 2003, just in time to see some of the changes wrought on this rooftop by the arrival of digital TV. In 2002, the east tower was partially dismantled and replaced by a taller structure (at left above), rising to within inches of 1500' above street level, 372' above the roof, to accommodate a new antenna for WBBM-TV and WBBM-DT (Channel 3) and a new FM master antenna.

WFLD and WGN both remain key tenants on the west tower - WFLD on top, WGN just below - but unlike WBBM, they're depending on the Sears Tower for their digital signals.

WYCC remains, both with analog on channel 20 and digital on channel 21, as does WGBO, now a Univision outlet with analog on channel 66 and digital on channel 53. (I'm pretty sure that's the WGBO antenna beneath WGN-TV on the west tower, and that WYCC is the big antenna in the foreground of that east tower picture at left.)

Channel 44 moved to Sears in 1999, and Channel 38 followed last year - we'll see where it went in an upcoming edition of Site of the Week.

That's the new WBBM-TV/DT antenna at the top of the east tower, with the FM master antenna beneath the round metal ice shield below it.

The old Alford antenna is still there for auxiliary use, in the foreground of the west tower image at right, with the old channel 2 backup antenna just above it, though hard to see in its new coat of white paint.

And of course radomes on both towers enclose ENG (electronic news gathering) microwave receive antennas for WBBM, WGN, WFLD and WGBO as well. One more note about the reconstruction of the east tower: not only did it make the east tower noticeably taller than the west, but it also brought about a more subtly noticeable change to the appearance of the building: the orange-and-white paint job seen in 1986 has given way to an all-white paint job and strobe lights.

One thing you can't tell from street level as you look at the Hancock: the roof is really a two-level affair. Stairs to the 100th floor lead to a mechanical level and a sort of submarine-porthole door out to the lower roof level, which is really more of a broad walkway around the tower. From there, an outdoor flight of stairs leads to the top of that 100th floor structure, where the space between the two masts is filled with a grid of suspended cables, two-way antennas, obstruction beacons and other assorted whatnot. That's where I shot the views below, looking south toward the Sears Tower.


The first hundred feet or so of each tower is actually an enclosed cylindrical structure about 15 feet across; I got to peer inside the east tower base from a doorway inside the 100th floor, from which you can see various transmission lines heading up to the sky.

One more note before we head back downstairs to see some of the transmission gear: the Sears Tower just doesn't look that much taller from here, although of course it is. (And both are much taller than One Prudential Plaza, which barely reaches 900' even with its antenna mast, which served as the primary transmitter site for WGN-TV before the Hancock went up. The other major Chicago transmitter skyscraper, shorter still, was the Marina City complex that WBKB-TV, channel 7, and WFLD called home in the late sixties and early seventies.)

Our rooftop adventure complete (and the sun rapidly setting over Chicago), we head back downstairs to the 97th floor, where more transmitter excitement awaits. Univision Radio chief engineer Paul Easter Sr., our guide for this exciting day of Chicago radio, takes justifiable pride in his transmitter room at WOJO (105.1 Evanston), where he presides over a row of transmitters that includes a Continental 816R, a Harris Platinum Z and a working CCA FM-10,000S for auxiliary use. WOJO is, I believe, the very first Chicago FM station to put Ibiquity's HD Radio (IBOC) system to use. WOJO's room also boasts a basic but workable emergency studio setup - and in the window looking north sits a traffic camera for WBBM-TV, showing commuters just how bad the traffic is this afternoon on Lake Shore Drive.

Down the hall from WOJO, our hardy band of transmitter fans (from as far afield as Boston, Dubuque, Akron and Fort Wayne) gets an added bonus: a quick tour of WFLD's analog transmitter plant, with those big Harris blue boxes for visual and aural transmission.

Also on 97 is the FM combiner plant, where the nine stations that share the master antenna (WBEZ 91.5, WNUA 95.5, WLUP 97.9, WFMT 98.7, WUSN 99.5, WNND 100.3, WKQX 101.1, WVAZ 102.7 and WOJO 105.1) send their signals before they're routed up to the master antenna. The combiner sits in a cage in the middle of the room; the window space is leased to TV broadcasters for fixed microwave links to various Chicago points of interest (we saw several dishes aimed at the United Center for WGN-TV Bulls broadcasts, for instance.)

As you can see from the window at the far end of the room, it was already well past sunset as we headed back to the service elevator, down to the concourse and back out to the cacophony of a downtown Chicago evening. And our big day of radio was far from done - join us next week as we show you the Univision Radio studios, the Clear Channel studios and a quick peek at a Sears Tower site!

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