Sutro Tower

San Francisco, California

The Sutro Tower Antenna Installation Project

Sutro Tower could not hold all of the existing antennas for analog operation and all new antennas for digital operation at the same time.  There wasn't enough space and the structure couldn't take the weight.  So a system of combined antennas was designed to support all of the new digital television stations.  In 1998 these temporary UHF antennas were installed on the tower.
The first digital stations went on the air in November 1998 using these antennas.  Each station had an analog transmitter and a digital transmitter on the air until the end of analog operation on June 12, 2009.  The antenna project for Sutro Tower was designed so that once the analog transmitters were turned off, the antennas that were used for analog could be removed, making room atop the tower for new permanent antennas for digital operation.
Auxiliary antennas would be needed for digital operation when maintenance on the tower or on the regular antennas prevented the use of the regular antennas.  New UHF antennas, designed for combined operation, were installed as the new auxiliary antennas for digital operation in April, 2009, between levels 3 and 4 of the tower.  This is a close up of the UHF auxiliary antennas.
KGO, the only VHF station on Sutro Tower, has a separate auxiliary antenna on level 1 of the tower.
The initial date for the end of analog transmission was set for February 17, 2009, but just prior to that date Congress passed a bill extending the transition date to June 12, 2009.  A few stations turned off their analog transmitters in February, but most of the analog transmitters remained on the air until June 12.  This change of date caused the antenna project at Sutro to be delayed by four months.
Work began with the removal of the old KGO, KBCW and KOFY analog antennas from the south east mast in June.  New antennas were then installed for KGO and KBCW.  These distant shots, taken from the east, show work on the south east mast during the installation of the KGO and KBCW antennas in July 2009. Photos by Morris Fung.
This photo shows the top of Sutro Tower as seen from the east on July 26.  Work is complete on the south east mast and the crew has now begun work on the west mast.  Shown are KGO 7's antenna at the top of the south east mast with KBCW 45's antenna below it.

Phillystran Guy Lines
The guy cables on the upper masts are manufactured by Phillystran. They are RF transparent. They're very large diameter, very strong, and very expensive.

Here's a link to Phillystran:

These are the Phillystran guys on the ground prior to installation.  To give you an idea of the size of the cable, that pin in the connectors is at least 2 inches in diameter.  All cables have to be cut to exact size and terminated at the factory.  Photo by Don Hackler

The KGO 7 and KBCW 45 antennas
Close up shot of the new KGO 7 antenna
Close up shot of the new KBCW 45 antenna (not yet being used)
Close up shot of the three masts as seen on July 26
Close up of the west mast with gin pole attached.
You can still see the old analog batwing antenna on the mast.
The old channel 4 and 5 analog batwing antennas were lowered to the ground July 28.  Here is an updated view of the tower, taken from my living room window on August 3, showing the shortened mast.
The following photos, taken by Don Hackler of KCSM and KCNS, show the old channel 4 and 5 batwing antennas on the ground.

You might have noticed an FM antenna on the right side of the tower not shown in the tower diagram.  This is a temporary antenna for KOIT 96.5 MHz. Their regular antenna is on the north tower, which will soon be dismantled.
Here are photos taken on August 4:

This one, taken from my living room window, shows a crew member on the mast.

These next two photos, taken from Twin Peaks, show that part of the old channel 2 batwing still remains.

These photos, taken by Bob Hofert, Engineering Supervisor, KTVU Fox 2, show the remains of some of the old channel 2 batwing on the ground.

This view from my living room window on August 7 shows what little is left of the old west mast.
Later on August 7: The tower crew brings down one of the last 12 foot long, 12,000 pound sections.  Photo by Bob Hofert.

Continued on Page 2

Photos and text by Larry Kenney unless otherwise indicated.

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