The AM-21 is a relatively new Digital TV tuner, and it's as capable as any other current DTV tuner in receiving local stations. In other words, if you're not getting stations, unless you have a dud, the AM-21 isn't the problem.
Sometimes, DTV reception is as much art as science. For full power station reception, assuming you have no physical obstructions (like mountains) between you and the transmitter tower, 50-60 miles is usually the limit. Having said that, exceptions always apply.
To get assistance with Digital TV over-the-air reception issues, go to TV Fool.com, enter your info, then post it at AVS in a new topic, in the HDTV Technical Forum.
You'll get advice from members with extensive OTA reception experience, who can usually tell you if reception of a given station is possible, and who will make specific hardware and set up recommendations.
Also, on the FOX 41 web site, they offer assistance with DTV reception issues by calling (509) 448-2828. They are a low power station, so I would imagine they have experience in helping with reception issues.
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