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Big California AM RF Project Is on Schedule

SoCal station KBRT hopes to switch on its new 50 kW system in early December

The big KBRT(AM) facility project for Crawford Broadcasting at Oak Flat in southern California continues apace and on schedule, according to DOE Cris Alexander.

He said all four towers are up, the prefab building is in place and assembled, and the block screening/security walls are just about finished.

Here’s an example of how mortar-filled concrete block walls are being used to screen and protect the prefabricated ThermoBond transmitter building.
It’s not every day that a broadcaster builds a 50 kW AM facility. This station, airing on 740 kHz and currently licensed to Avalon, Calif., has its transmitter site on Catalina Island. It seeks to change its community of license to Costa Mesa. The Oak Flat antenna site in the Santa Ana Mountains near Silverado in eastern Orange County was once used by KPLS/KLAA(AM).

KBRT will increase daytime power from its current 10 kW to 50 kW, via a directional array made up of four 281-foot towers and pointing to the southwest. Its format is Christian talk, its slogan “celebrating the local body of Christ.”

Operations Manager Todd Stickler dry fits a piece of 3-1/8-inch rigid line. Rigid is being used for all interior RF plumbing. The towers were manufactured by Magnum and installed by P&R Tower out of Sacramento. Other project work is being done by SWB Enterprises out of L.A.

Edison, the electric utility, pulled in the primary feed conductors and set the transformer and meter. “The transmitter and phasor are in place,” Alexander said. “Antenna tuning units have been shipped and will be delivered on the 22nd. P&R Tower will be back at the site on the 23rd to pull the transmission and sample lines along with power, control and fiber-optic cables into the already installed underground conduits.” Alexander is also a contributor to Radio World.

Two runs of the rigid line are complete to the six-port egress panel through which they will pass to the outside. Rubber compression boots will make for a weathertight seal around the lines.
As RW reported in 2011, Crawford had to engineer this facility to essentially duplicate the location of its existing interfering and protected contours. Its neighbors include KCBS to the north in San Francisco, KIDR to the east in Phoenix and KFMB to the south in San Diego.

This is a simulation of what the station array will look like. See photo simulations of the completed antenna system here (PDF). Tell Radio World about your own interesting studio or RF project. Email [email protected].

KBRT’s Tower Move Progresses (Nov. 2011)