WASHINGTON — Americans worried about losing their television signals due to the approaching transition to digital broadcasting have requested more than 4.4 million government coupons to help pay for special converter boxes.

Beginning Feb. 17, the Department of Commerce will begin distributing them. On the same day, three major retailers are expected to begin selling the boxes, the agency said Thursday.

Full-power television stations will stop broadcasting an analog signal Feb. 18, 2009. Anyone who does not own a digital television set and still gets their programming over-the-air will need to buy a box. Viewers who have satellite or cable service will not need one.

Last month, the government began accepting orders for the $40 coupons. Each household is entitled to two coupons, which look more like credit cards. The coupons expire 90 days after they have been mailed.

The three chains that will begin stocking the converter boxes are Best Buy, Radio Shack and Wal-Mart. Those stores and many other retailers "should be able" to accept the coupons, according to a department press release.

Also on Thursday, a Washington D.C. Best Buy demonstrated its own box, which will retail for $59.99. Present were Commerce Secretary Carlos Gutierrez and Federal Communications Commission Chairman Kevin Martin.

To request a coupon, consumers can apply online at www.dtv2009.gov. The government also has set up a 24-hour hot line to take requests, 888-DTV-2009 (888-388-2009).