IF WE MAY interrupt the program in progress on most public airwaves--"The Tight Money Game" --station breaks are in order this month for two pioneer outlets of non-commercial broadcasting. Neither WETA-TV/Channel 26 and WAMU/88.5 knows what the onslaught of U.S. government austerity will do to public programming, but both stations have been defying extinction and impressing audiences for 20 years.

We tend to believe that most such institutional birthdays are best celebrated internally, for age alone is certainly no great measure of an organization's contributions to a community. But these are instances in which the contributions have always gone in both directions--and the organizations happen to belong to everybody. And before any older- timers start singing the praises of early public broadcasting, it should be noted that, in truth, much of the that initial "educational" fare was grim fodder even for the highest of brows.

Back then, much of the non-commercial programming was from academe, served in overly generous blocks of airtime--when the broadcasters' idea of down-home comedy was light opera and when sports meant a marathon lecture. But in Washington--partly because of its capital importance and partly because of its generosity with capital--both WETA and WAMU grew up to branch out and appeal to wider audiences.

And while non-commercial television generally tends to attract more of the praise, criticism and dollars than does public radio, WAMU's strong 24- hour-a-day signal has succeeded in attracting nearly 10,000 subscribers and some 130,000 listeners a week. Gone are the days when the morning highlights included Swedish lessons or--and this was true--instruction on how to figure out the day of the week for any date in history, or how to memorize the books of the Bible in order. Today, a remarkable variety of news, music and information is coupled with direct coverage of congressional and local meetings and lively talk shows.

If there is a message from the sponsors, it is the same one that WETA and WAMU audiences have been hearing for all these years, but now more than ever: keep those cards and dollars coming, and rewards will be offered.