iHeartMedia filed an application with the FCC on November 11, 2021, for a Minor Modification to relocate their KOGO (AM) 600 kHz transmission system to the current KGB-AM (formerly KFMB-AM) 760 kHz site at the western boundary of Santee.
The move is part of the sale of the land under the KOGO towers by Vertical Bridge to a residential developer. KLQV (FM) 106.5 and KWFN (FM) 97.3 will also need to move and KWFN has filed to move to the nearby KGB-FM tower.
The three 314-ft towers are only 69° long electrically at 600 kHz, meaning they’ll be less efficient, and iHeart has no plans to add capacitive hats. AM towers are generally 90° to 225° tall. With more site sharing, the FCC is approving many new configurations. The new transmitters will need to output 9 kW daytime and 10 kW nighttime rather than the 5 kW they produce now. The antennas for KGB-AM 760 were aligned to provide a sharp null toward WJR Detroit. The current KOGO day and night antenna pattern provides some reduction of signal to the east and north but doesn’t require deep nulls, making the engineering significantly easier.
One interesting component is the potential for additive intermodulation between 760 and 600 kHz creating a beat at 1360 kHz, interfering with the reception of KLSD (AM), another iHeart property. The interference zone can be managed with filtering and corrosion prevention but will be difficult to eliminate entirely since cars on highway CA-52 pass actually between two of the site towers. Driving now between the KLSD and KOGO towers on CA-94 can similarly produce a subtractive product that interferes with KGB-AM, so this isn’t an issue new to San Diego. The extent of the effect can depend on the quality of the car radio.