Several Web sites have been dedicated to helping millions of Americans make the conversion from analog to digital TV. While government Web sites and instructions for installing the converter box make it sound simple, there are several potential complications that consumers should be aware of.

Among them:

• The $40 government coupons to help pay for converter boxes, being offered free to consumers at www.dtv2009.gov or by calling 1-888-388-2009 toll free, expire in 90 days. Reports vary as to whether that 90 days begins when a coupon is requested (often at least three to four weeks before it is received) or from the date it is mailed. Once it expires, retailers won't accept it and consumers aren't able to get replacements.

• All boxes are not created equal, despite reports by some agencies that there are few differences. Check online ratings and Web sites that compare boxes and features, including www.dtvusaforum.com.

• Once the $40 coupon has been used to purchase a box, the retailer will not refund either the coupon or cash if the box doesn't work. While troubleshooting phone numbers are provided, consumers are on their own to determine whether a problem exists with the box itself, the cable connections, the TV or the antenna.

• The coupon is only valid for certain boxes at specific retail outlets and can't be used for more costly units.

• The box is designed to provide a simple connection from wall antenna or rabbit ears to a TV. Any additional equipment like DVDs, VCRs, tuners or other AV equipment creates complications for hook-ups that aren't explained in the instructions that accompany many units.

• While many existing TV antennas will work with the boxes, others may not provide a sufficiently strong signal for the box to function properly, meaning there won't be any reception at all through the box unless the antenna is either repositioned or replaced.

• Converter boxes come with one cable to connect it to the TV and antenna. Additional cables will be necessary to hook up any other devices.

• Many consumers have reported they receive fewer channels with the box than they did without it. Others report that the box functions fine for a few days or few weeks, then quits working altogether.

For more information, see www.tvconversionhelp.com, www.digitaltips.org, www.dtvtransition.org and www.ceaconnectionsguide.com.

— Carrie A. Moore