WMAQ-TV's antenna atop the John Hancock Building, overlooking
Lake Michigan. WMAQ-TV's antenna is on top of Chicago's 100-story
John Hancock Center and is 1,456 feet above the street. It went
into operation on October 1, 1969. The transmitter is an RCA
TT-30 FL-1, which is actually two 15kw transmitters operating
in parallel. These are operated at only 5.4kw output for a total
of 10.8 kw into the transmission line. ERP is 40.1kw visual
and 2.36 aural. If one transmitter fails, the other doubles
power to maintain service. The other unit may then be repaired.
Further protection for service is provided by duplicate power
feeds from two separate substations and duplicate cooling air
supplies. The antenna is split into upper and lower halves,
and each half may be fed with double power. In event of diplexer
failure, aural may be fed to one half and visual to the other
half. If the whole antenna is wiped out, an emergency antenna
on the other tower may be used.