Some residents in parts of Windward O'ahu, Moloka'i, the Big Island's Hamakua Coast and some pocket areas of the islands may not have TV reception tomorrow after 12:01 p.m. even if they use new converter boxes.

That's when Hawai'i's TV stations switch their over-the-air signals from analog to digital. Hawai'i is the first state to switch under a federal mandate requiring conversion by Feb. 17.

For residents with relatively new digital TVs or with connections to cable or satellite television, there will be no change in how they get their signal. Nor does the switch affect Kaua'i, where a lower-power transmission is excluded from the mandate.

But an estimated 23,000 households statewide with older TVs will need a converter box to keep receiving TV signals over the air through their antenna.

Even with the box, households that catch the over-the-air signal from Maui may be out of luck. The conversion is being timed with moving the main Maui transmission tower from the top of Haleakala down to the 4,000-foot level of Ulupalakula Ranch.

That lower elevation might mean more interference with the signal. The other main towers are in Makakilo.

The tower is being moved from the Haleakala summit because of concerns from the astronomy community, and the move is timed to avoid disturbing an endangered Hawaiian bird's annual nesting and breeding period. The habitat of the Hawaiian petrel, or 'ua'u, is near the new tower.

"We think a good percentage of the population is ready for the transition," said Chris Leonard, president of the Hawai'i Association of Broadcasters. "But we won't know until we switch on Thursday.

"We're not absolutely positive on the complete extent of the change of coverage for the areas that had received over-the-air coverage."

Most of Hawai'i's 450,000 TV-viewing households subscribe to cable or satellite networks, which are unaffected by the conversion. So many people use cable and satellite here because the mountains make it difficult to catch over-the-air broadcasts in many locations.

About 4 percent of households statewide rely on rooftop antenna or rabbit ears to catch over-the-air programming. Nationwide, at least 19.6 million households get only over-the-air signals and 14.9 million others have secondary over-the-air TV sets.

HAWAI'I FIRST TO SWITCH

Hawai'i is the first state to convert, so many people on the Mainland are studying our conversion, said Lyle Ishida, Hawai'i DTV transition manager for the Federal Communications Commission. To date, only cities in California and North Carolina have switched.

"Ultimately, the switch means the consumer will have better access to a quality picture and ultimately more channels," Leonard said. "The analog spectrum will be available for emergency services and will enable new communication devices to use the analog spectrum."

To ease the financial burden for residents, the federal government has issued 90-day coupons worth $40 to residents, of which 13,872 have been redeemed in Hawai'i.

It is still possible to apply for coupons, but there is a waiting list. Many retailers have sold out of their converters, but some offered to accept the coupons and have the converters shipped directly to residents, Leonard said.

Hawai'i residents' requests for coupons totaled 53,012.

"There are coupons available," Ishida said. "Not all cards (coupons) issued have been used and as they expire, we are reissuing them."

Several stations are broadcasting in the digital format already, Ishida said. Consumers should have their boxes plugged in and in use already. No need to wait until tomorrow, he said.

Don Bocok, a Mililani resident of 35 years, had his converter box installed months ago. It was hassle-free because he applied to the FCC for free hook-up.

"We have no need for cable at all," Bocok said. "I am still using rabbit ears and we were able to catch 12 or 15 stations.

He might even pick up more channels with the digital converter box than before, Ishida said. For sure, he'll pick up a TV schedule broadcast over the air.

"It was a pleasant experience," Bocok said. "All we have to do is when all the stations go on mandatory (digital signal) on Thursday, we'll have to rescan the remote and pick up whatever channels we can."