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What happened to Sutro Tower’s antennae?

Tower’s southern mast comes up short

Something strange has happened to Sutro Tower, the three-pronged broadcast apparatus near Twin Peaks and most visible structure on San Francisco’s west side.

One of the enormous tower’s three trademark prongs has been missing in action for weeks, leaving the structure looking displeasingly asymmetrical from some angles and prompting San Franciscans to wonder what’s going on with the western landmark.

David Hyams, a spokesperson for Sutro Tower, tells Curbed SF not to worry as the disappearance is not a permanent alteration and is the result of technical upgrades to broadcast equipment.

“One of the three masts at the top of the tower is being taken down and completely replaced,” says Hyams. “When the project is finished there will be nine new or replacement antennas on the tower.”

Each antenna weighs thousand of pounds. The tower’s southern mast must be rebuilt in order to support the new equipment—hence its disappearing act.

When work is complete on the new mast and attached antennas, it will resemble the older equipment to the eye of distant observers, and the tower’s recognizable profile will be restored.

The San Francisco Planning Commission approved the construction in July. According to a Planning Department report, the replacement work is meant to satisfy federal technical requirements “to accommodate the Federal Communications Commission (FCC) spectrum repacking requirements.”

(“Spectrum repacking” refers to mandated changes in the frequencies broadcast stations use.)

At the time, the plan was to “add seven new broadcast antennas, replace four existing broadcast antennas with new antennas, and remove four existing broadcast antennas” from the tower.

In all, the city issued six building permits for work on the tower, starting in August. Hyams adds that the work “is extremely precise” and conducted some 900 feet off the ground.

At 834 feet above sea level, the base of the tower sits at one of the highest points in the city. The structure itself is 977 feet and consists of approximately 3.5 million pounds of steel.

Sutro Tower began broadcasting in 1973, replacing a similar but shorter tower nearby that wasn’t quite powerful (or tall) enough to reliably service the entire city.

Like almost any structure of sufficient size, the tower attracted complaints about its effect on the skyline before and after construction. Herb Caen once remarked, “I keep waiting for it to stalk down the hill and attack the Golden Gate Bridge.”