Metrocable television, available only to residents of Arlington, is an answer to National Hockey League fans who annually bemoan the absence of the Stanley Cup playoffs on the conventional networks.

Through an arrangement with Madison Square Garden's cable television system, Metrocable will pick up NHL playoff contests being played on Saturdays and all of the New York Rangers' home playoff matches.

Metrocable will show the Saturday Rangers' game against the New York Islanders in Uniondale, N.Y.

Metrocable offers a variety of sports programs, some of them taped. Gaithersburg has a cable television system, but no regularly scheduled sports events yet.

Jan Schwenzer, marketing manager for the Arlington system, says installation can be arranged in a couple of days, at a fee of $25 to connect a coaxial cable from a telephone pole outside a house to a television set.

There is a monthly charge of $16.90 for programs, including first-run movies.

The metrocable service offers programs on 25 channels, including those shown on conventional television stations in Washington, Baltimore, Atlanta and San Francsico.

Sports pickups have included games of the Baltimore Orioles; Atlanta Braves, Hawks, and Flames; New York Knicks and Rangers, and the Golden State Warriors-"with better reception (than with conventional stations) and with no interruptions or commercials," according to Schwenzer.

Through its Home Box Office service, Metrocable will show the finals of the Amateur Athletic Union inter-city boxing tournment finals (taped) on Wednesday (May 2) and Saturday (May 5).