KHCT racks: Harris FlexStar exciter, Belar analog and HD monitors, Bird BPM series power monitors, backup Orban Optimod 8100 and TTC 8090X Exciter, Starlink dual receivers (space diversity) and Hitless Switch, Davicom MAC+ remote control, UPSs

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The plan included supplementing existing Harris Z-Series solid-state transmitters with new high-power Harris HPX tube HD transmitters. The plan also revisited combining methods for the best possible efficiency, and required adjustments to HVAC and other systems to accommodate the high-power tube models. The primary engineering goal was to minimize equipment and ongoing utility costs.

KHCC, serving about 600,000 listeners, was the driving force for the entire project - though it was the final of the three upgrades to go live. Projections suggested that the move to -12dBc would significantly enhance HD Radio service to more than 385,500 people within the 60dBu contour, including the three principle cities. A Harris HPX40 transmitter - as in 40kW - was chosen for this site as it could provide -9dBc digital at 13,230W FM required in the transmitter combining plan.

KHCD was the first site to upgrade in the fall of 2011. We lit up an HPX30 (30kW), with just a bit of re-tuning required to operate through a combiner with the Z12HD+ for -14dBc operation. KHCT, at an asymmetrical -10/-14dBc, soon followed. We turned on an HPX20 (20kW) that ran right out of the box, with no combining. In February, KHCC's HPX40 went on the air, providing a digital signal at -12dBc in conjunction with a Z16HD+.

Combining options

KHCT: Exciter rack with Harris FlexStar, backup Orban Optimod 8100 and TTC 8090X Exciter, Belar IBOC monitor, Bird BPM wattmeters and the two transmitters: Z6HD+ and HPX20

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Radio Kansas underwent an intense period of research to determine the best possible method. We had been operating in the split-level combining method since launching HD Radio services. That method used one legacy transmitter for FM-only and a second transmitter for FM+HD. This was efficient at -20dBc.

The search was on to identify the most cost-effective way to upgrade the digital injection level from both a capital standpoint and with consideration of the ongoing operating costs. Power is increasingly expensive and makes up a significant portion of the Radio Kansas budget.

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