If you persist in believing that Congress is a mix of blandly telegenic hotshots with natty suits and blow-dried hair, it is time to pause and pull up a chair next to Rep. Claude Pepper (D-Fla.).

To talk with Claude Pepper, at 79 the oldest member of the House of Representatives, is to have the sterotype knockd to flinders.

He's not all that telegenic, he's not the picture of three-piece nattiness and he wears a reddish toupee. But at an age when others might just pack it in -- or ought to -- Pepper is running hell-bent-for-leather to get the country straightened out.

His cause is the plight of the elderly in America and his forum is the chairmanship of the House Select Committee on Aging, a generally powerless tool that Pepper has converted into a buzz saw.

The picture painted of the elderly by Pepper, flecked with statistics of pain and loneliness, is not quite the image left by those warm television and magazine ads depicting the pleasure of the Golden Years.

Roughly 11 percent of the U.S. population is 65 years old or more, for example; and at least one-sixth of these people live below the official poverty level.

And "it's very lonely for many of these people. There is so much we could do for them, but there still are a lot of people [in Congress] who are mixed up in their evaluation of what's important," Pepper said the other day.

He had another thought. "It's a strange thing," Pepper continued. "We are warm and humanitarian in so many respects. But in others, we don't get around to being humanitarian."

As chairman of a "Select" committee -- an advisory, investigative body than cannot produce legislation -- Pepper is somewhat limited in the ways he can force humanitarianism upon his legislative brethren.

One way, however, is by making himself a general nuisance, appealing to each of the 10 committees and 30 subcommittees of the House and staying after the administrators of 132 different federal programs that affect the elderly.

"Pepper and his committee have been able to draw a lot of attention to senior-citizen problems" said an oficial of the National Council of Senior Citizens, a lobbying outfit with 3.5 million members.

"We're all for Claude Pepper. He's very visible. A lot of his hearings tend to be flambouyant -- tend to be publicity-oriented. We'd like to see more bills passed, however."

Pepper is not fazed by the indirect criticism, for he knows that understanding of a problem must occur before the Congress will come to grips with it legislatively.

So he and his committee have been hammering away with hearings and reports about the inadequacy of Medicare and Medicaid; about the mistreatment of elderly mental patients; about abuses in private medical insurance programs; about inadequate housing and boarding facilities for the aging.

Pepper's haranguing, for one thing, led to abolition last year of mandatory retirement rules before age 70 in private business. For another, he got a 30 million program approved to combat crime in public housing projects dominated by the elderly. This year, he and Rep. Thomas A. Luken (D-Ohio) were behind an amendment that cut Amtrak fares for the elderly.

If there is a rhythm and cadence to public lives, this period has become a musical interlude in the career of a man who is, unlike most of his younger colleagues in the House, a certified historical figure.

Pepper was elected to an unexpired Senate term in 1936, then was reelected in 1938 as a solid Roosevelt New Dealer. He was a strong critic of Hilter's growing power and, for his support of military conscription in 1940, was hanged in effigy on the Capitol lawn.

By 1943 he was badgering Congress to adopt a program of "universal health insurance" -- an idea he still is pushing -- and speaking in favor of civil rights. Just after World War II, he was roundly denouncing the House Unamerican Activities Committee investigations for "undermining" Americanism.

That all caught up with him in 1950 when he was defeated in the Florida Democratic primary by George Smathers Sr., in one of the bitterest, nastiest campaigns of modern times.

Suffice to say that he was referred to as "Red" pepper. "You can see why I lost. I was for civil rights and national health insurance. They had$2 million and I had $200,000. But 'communism and nigger' that's all there was. It was the smear-red tactic" he said.

So Pepper went back to practicing law in Miami, then won election to the House in 1962 when a new district was created in Dade County. The district is heavily Cuban and heavily black with more elderly voters than average and Pepper has has no trouble retaining the seat.

There is a tinge of regret in Peppers reminiscences about no longer being in the Senate. Had he stayed, he now would be president pro-tem and very likely chairman of the Foreign Relations Committee, which appealed to him greatly.

But it's another career now, and Pepper, stunned by the death of his wife from cancer last March, says he intends to spend the rest of this time here -- at least until the year 2000 -- working on health problems and being an advocate for the elderly.

"I think we've given the elderly a little more hope, a little more motivation through the work on our committee," he said "But we still have so far to go."

Next week, he'll be treating Congress to another angle on the story of aging -- flavored with Pepper. He has scheduled a hearing at which none of the main witnesses will be younger than 100, because, he thinks they have wisdom to offer.