Post by Matt Blaze

AT&T Long Lines "Oak Hill" Tower, San Jose, CA. 2021

All the pixels, but operator assistance is no longer available, at https://www.flickr.com/photos/mattblaze/51261791084

#photography

Captured with the Rodenstock 50mm/4.0 HR Digaron-W lens (@ f/4.5) on a Cambo WRS-1600 camera (with about 15mm of vertical shift to preserve the geometry), the Phase One IQ4-150 back (@ ISO 50) in dual exposure mode (which preserves a couple stops of additional dynamic range into the shadows).

The tower's shape is irregular; it tapers slightly.

The wide angle and panoramic orientation give a bit of context, alone on a hill (which is being rapidly encroached by adjacent residential development).

For much of the 20th century, the backbone of the AT&T "Long Lines" long distance telephone network consisted primarily of terrestrial microwave links (rather than copper or fiber cables). Towers with distinctive KS-15676 "horn" antennas could be seen on hilltops and atop switching center buildings across the US; they were simply part of the American landscape.

Most of the relay towers were simple steel structures. This brutalist concrete platform in San Jose was, I believe, of a unique design.

@mattblaze
A friend of a friend bought one of those sites, primarily to get the diesel generators that made the mechanical UPS power supply. A motor spun a heavy flywheel as long as there was utility power. If the power failed, an electromagnetic clutch dropped out, the motor turned into a generator and the flywheel spun up a diesel motor to power to the electronics at the site. There were two such generators on the site. They had to be serviced on a regular basis but we're in fine shape. One such motor/generator was a heavy load for my utility trailer.