VISIBILITY HANDICAP: Teased in the business as the "Doogie Howser Sports Network" for its young and ambitious staff, Mizlou Communications' Sports News Network has grabbed the attention of the nation's sports junkies who can't get enough updates.

Its biggest obstacle so far has been visibility, which currently is limited to about 35 percent of the nation's 50 million cable households. Thirteen of the top 30 cable systems in the country, including No. 2, ATC Time Warner and its 6.9 million subscribers, have tapped into SNN.

The only Washington link to the seven-month-old, round-the-clock network is Media General Cable in Fairfax County (173,000 subscribers).

"The next step is to make service available in the top 25 markets as soon as possible," SNN Executive Vice President Jon Steinlauf said. "Our strength has been the East Coast, Florida and Detroit. . . . But without distribution, this network doesn't work."

As with most upstart networks, Mizlou is losing money on SNN and has made it known it is looking to sell a majority share in the next two or three months.

MORE ON REDSKINS: Home Team Sports has added a third Redskins studio show to its lineup. "The Mark Rypien Show" debuted last night and will be seen Thursdays at 7:30, preceded by "Redskins Preview" with Bobby Mitchell and Johnny Holliday at 6:30. The other program is "Redskins Magazine" with Tony McGee and Rick "Doc" Walker on Mondays.

Channel 5's preseason special, "Redskins '90: A Look Ahead," will be Saturday at 7:30 p.m., hosted by Steve Buckhantz.

KOKEN ON HTS: HTS announced yesterday that former Capitals announcer Al Koken will handle the pregame shows and sideline reporting for the Capitals and Bullets broadcasts this season.