"Hold it, hold it just a minute," said Frank Mankiewicz."I want to hear the sign-off."

Mankiewicz, president of National Public Radio, turned up the volume as correspondent Linda Wertheimer wrapped up another historic radio broadcast yesterday from the Senate Chamber.

"I get goose pimples just listening to it," said Mankiewicz, ecstatic over NPR's coverage of the Panama Canal treaties debate, the first time a Senate debate has been broadcast live.

Since the debate began Wednesday, NPR has aired 14 hours of debated and commentary by Wertheimer, sitting in the front row of the radio-television gallery. "More people have heard this on radio than have ever heard (a Senate debate) before a history," said Mankiewicz.

How did NPR pull off this coup?

"It's a little bit like the little boy who goes in and asks for something and gets the answer. 'Why not?'" said Mankiewicz. "All the networks have been trying for some time, but they've really been thinking about TV. I think there's been no radio before because nobody has seriously gone in and asked."

Mankiewicz said he reached agreement Monday for the live broadcasts with Senate Majority Leader Robert Byrd who was "very forthcoming." Mankiewicz said NPR was granted the four things it wanted: a correspondent on the scene, the technical control to "turn down" the activity on the Senate floor and bring in the voice of the correspondent, and "ambient" microphone with the capacity of picking up background noises, and a day of rehearsal.

Mankiewicz believes the presence of NPR - the changes in Senate rules apply only to broadcast of the Panama Canal debate - is having a noticeable affect on the senator's behavior.

"They're not spending time on anything other than the debate. And the proponents of the treaty, and today the opponents, are not allowing the other side to make speeches: They're interrupting to make points."

This could happen if the senators can remember one thing about the microphones in front of them, the only techniacl problem encountered so far. Sometimes a speaker will put his microphone into his breast pocket - other senators on the floor can hear him but it doesn't play that well in Peoria, or wherever on the 211-station network.

In Washington, the historic broadcasts are being carried by WETA-FM and also may be heard in the evening on an edited version over WAMU-FM. After today's broadcast, coverage will be resumed Feb. 21, when the Senate resumes debate. Mankiewics estimates the cost for four to five weeks of coverage at more than $100,000.

The NPR head said that Byrd respected the team putting on the broadcast - Werheimer, a six-year veteran anchor for NPR congressional and political coverage, and the enginee working in the Senate Chamber, Gary Henderson.

"Byrd is a bluegrass fan and Gary Henderson is a bluegrass deejay on WAMU," said Mankiewicz. "The signal goes to West Virginia. I've assured the Senator he can have a guest shot anytime. He can come on and play his fiddle."