The usual summer doldrums that descend on the sprawling headquarters of the North Atlantic Treaty Organization vanished when Peter Alexander Rupert, the sixth Baron of Carrington, took over the alliance's senior post in late June.

As NATO's new secretary general, Lord Carrington jolted the more ossified reaches of the bureaucracy and, by most accounts, infused the place with a newly dynamic work ethic that has been missing for many years.

He also has made clear that he intends to use the stature and experience that he acquired during his years as Britain's foreign and defense secretary to shake up the nature of his new job, which assumed largely figurehead status during the long tenure of the Netherlands' Joseph Luns.

Carrington, who will see President Reagan Tuesday during his maiden round of visits to allied capitals, wants to put a greater accent on the political dimension of NATO.

"There has been a concentration in the public minds about NATO in its purely military form," Carrington said in a wide-ranging interview. "But we should concern ourselves just as much with trying to find solutions to political problems that can allow us all to live under less tension."

In a speech last year at London's prestigious International Institute for Strategic Studies, Carrington warned about the limits of what he described as "megaphone diplomacy" in finding political solutions to allied misunderstandings and East-West conflicts.

The phrase reflected European concerns that confrontational rhetoric in the early days of the Reagan administration contributed to the worsening relations with the Soviet Union.

Today, Carrington feels that Washington has enhanced its image in Europe by adopting a more moderate tone and by permitting the Soviet Union to bear the responsibility for the hiatus in arms control after Moscow walked out of the Geneva negotiations on strategic and intermediate nuclear missiles last year.

"I really think that over the last few months the Reagan administration has played it absolutely right," he said. "The U.S. has made it perfectly plain it is willing to begin talks on space weapons and to start off again on the Geneva negotiations."

"I doubt that there is more for us to do at this time. What we've got to do is be persistent, and go on and on and on telling them that we are prepared to talk. The Soviets have locked themselves into a difficult position by walking out of Geneva, but they will return, and the sooner they do it, frankly, the better."

He said that public anxieties about the prospects of war have grown because "there has not been that much contact between East and West for the past five years and this has led, I think, to this fear that there is a proliferation of nuclear weapons and nobody is doing much about it."

Carrington believes that in some ways the alliance has become too self-denigrating and underestimates its own strengths, especially its ideological and economic influence in the world.

"The Russians must feel extremely alarmed in recent years about the events in Poland and the lack of glamour that Marxism holds for the world," he said. "Equally, they have an economic system that does not work. So I would feel we have nothing to lose from talking to the Soviet Union, because we don't talk from a position of inferiority."

In terms of the military balance, Carrington said that while it would be a mistake to become complacent, NATO countries should realize that they have "quite enough military and conventional power to defend themselves."

One of the primary factors behind the poor state of East-West relations, Carrington feels, may simply be that each side lacks a sound understanding of the other's motives and background.

"I think to sit around a table and talk to them is good," he said. "It would be useful for us to get to know them better, and them us.

"Maybe they will begin to feel, though perhaps they don't at the moment, that we genuinely do want some kind of relaxation of tension, arms control and less weapons in the world. They will hear from us that we are not prepared to put up with certain things like Soviet expansion into the rest of the world, and that if they want to get on with us they have got to understand that."

Helping to mediate the sporadic quarrels between the United States and the European allies is another area that Carrington expects will consume much of his time.

After more than three decades of involvement in alliance diplomacy, Carrington says he has learned to brush aside perennial talk about NATO's demise.

The controversy over the deployment of Pershing II and cruise missiles in Europe was a difficult test of alliance unity, he says, but the deployment was "an enormous success" because NATO emerged stronger by showing that it can fulfill its commitment.

But Carrington still foresees difficulties in reconciling U.S. and European attitudes about sharing the burden of defense spending.

He is worried by the renewed propensity of the Congress to link the continued presence of U.S. troops in Europe with more defense spending by the Europeans.

A recent amendment proposed by Sen. Sam Nunn (D-Ga.) called for the withdrawal of up to 90,000 American troops from Europe by the end of the decade unless the Europeans pay more for NATO's basic infrastructure and live up to previous pledges to maintain a 3 percent annual increase in defense spending.

While Carrington believes that the Europeans may come to realize that Nunn made a strong point "by in effect saying, 'what's the point of having new tanks when you don't have shells to fire with the gun,' " he is doubtful that the impact of prolonged recession will permit European countries to meet the 3 percent goal very soon.

Another topic that has caused consternation in Europe is the accelerating race to find space-based systems for antisatellite and antimissile purposes.

Carrington says that the Reagan administration's research effort so far in this area is "prudent and sensible," but that "a lot of questions remain to be answered about what such a defense system would cover and the problems in other areas, such as cruise missiles and nonballistic weapons that could not be intercepted."