KPBS-FM Lights Up on Soledad

After two decades of talk and planning, KPBS-FM finally completed its move to Mt. Soledad, beginning transmissions at 10:30 AM on Monday, October 1, 2012. The new coverage area better matches its listener profile of college-educated, relatively affluent coastal and north county residents.

Leon Messenie, Director of Engineering, said they are using the shared Dielectric make FM antenna known as “Quadzilla” along with host KFMB-FM 100.7 MHz, KIFM 98.1, and KBZT 94.9. The antenna, originally designed to carry 105.3 MHz, had to be replaced by KPBS to handle the lower channel. KFMB’s RF supervisor Rick Bosscher said that they were able to tune one of the combiner ports from 105.3 to 89.5, but came close to losing a tuning slug into the cavity doing so.

Besides the new antenna, KPBS RF Engineer Rockley Curless oversaw the installation of a new┬áNautel NV-20 transmitter outputting 9.4kW with an accompanying Ibiquity HD signal combined at low level. The station’s new ERP is 26kW non-directional. The station will lose some coverage in the shadows of east county hills, but gain much more coverage in the north county and La Jolla. The west-facing slopes of east county will continue to receive excellent signals.

One of the changes loyal listeners are likely to notice is full-time stereo. Yes, KPBS-FM used daypart scheduling to broadcast a monaural signal during talk programming. This extended their effective coverage area by hundreds of square miles when they eliminated that pesky little 19kHz pilot and L-R 38kHz subcarrier that fools a radio into demodulating it even when too weak, making for a noisy listener experience. For the time being, Messenie says they will keep the stereo pilot on full-time.

Messenie says the quest for a Soledad location began with an application in 1994 that was issued in 1997, but it was to be at the US Navy radio site and the person who granted permission to use the site was not authorized to do so, and permission was withdrawn. XETV in Tijuana fought other efforts to move KPBS, concerned that the FM signal would overwhelm its channel 6 TV signal in San Diego. That fight became moot in 2007 when the FCC ruled in favor of KSDS upgrading to 20kW 88.3 MHz signal at its Mesa College site, saying that there were no specific rules protecting US coverage of Mexican TV channel 6 broadcasters.

Will KPBS-FM will use its old site, where KPBS-TV continues to operate, as an aux standby location? Messenie says they plan to, but will have to install a directional antenna to keep its coverage within the new area.

They don’t have backup power on Soledad, but will work toward that end. The Soledad site has long been served by two electric feeds that switch automatically in the event of an outage on one side of the hill.

Project partners included Wireless Infrastructures for tower work, Juice Electric for electrical wiring, and Hammett and Edison for the RFR study.