The government's star witness in the bribery trial of former D.C. Superior Court judge Robert H. Campbell testified yesterday that he made between 10 and 15 cash payments to the judge, usually in $100 bills and in specific amounts requested by the judge.

The testimony of Robert P. Jenkins, a former high-ranking Bladensburg construction company official, was the first direct evidence that money was paid to the former judge, which Jenkins said was intended to influence Campbell to deal leniently with the construction firm's traffic tickets.

The government is relying heavily on the testimony of Jenkins, whom prosecutors have described as the company's trusted bagman. Prosecutors have said they will support his testimony with documents showing that cash was withdrawn from the construction firm's accounts near the same time that deposits were made in Campbell's bank accounts.

In methodical and oftentimes tedious questioning of Jenkins, Assistant U.S. Attorney John P. Hume at one point asked him, "And why did you make cash payments to Judge Campbell?"

"He asked for the money," Jenkins replied matter of factly.

"And why did you give him the money?" the prosecutor asked.

"I thought that it would help him in being lenient on the disposition of the traffic violations," Jenkins testified.

Jenkins' statements came during the fifth day of Campbell's trial on charges that he took more than $10,000 in cash and favors from Excavation Construction Inc. in exchange for his dismissal of hundreds of thousands of dollars worth of overweight-truck fines levied on the company between 1975 and 1977. Campbell and two co-defendants, the firm's general manager, Larry A. Campbell (no relation to the judge) and the firm itself, are all charged with bribery, conspiracy and racketeering.

Jenkins, on the witness stand for the second day, testified that when Campbell told him how much money he wanted, Jenkins would get an Excavation Construction cash voucher and a check, cash it at a bank, usually getting $100 bills, and then give the former judge the money, sometimes in his chambers and sometimes at his Northwest Washington home. Jenkins said the former judge sometimes counted the money in front of him. The former construction official also said that the two never discussed or exchanged money except when they were alone. The former judge told him he needed the money to pay bills, Jenkins testified, and that he tried to accommodate Campbell if he expressed an urgent need for the cash.

Under questioning from Hume, Jenkins testified that he made notes of the payments he made to Campbell, but destroyed them after his first appearance before a federal grand jury investigating the case. Jenkins was convicted of perjury for lying to a grand jury about the case and subsequently agreed to cooperate with government prosecutors. The government contends that Jenkins, whom they have described as the trusted, corporate "bagman," made seven cash payments to Campbell in amounts from $800 to $2,500.

Asked by Hume why he had destroyed the payment record, Jenkins testified, "I don't know what made me do it, I just did."

When Hume asked Jenkins if untraceable cash payments were the "safest" method to transmit the money, Jenkins responded, "Yes."

Jenkins said that when he gave Campbell cash, they occasionally discussed tickets on overweight trucks. He also testified that tickets were accumulated by the construction firm until they could be taken for handling by Campbell instead of another judge.

"And that is what you were paying him for, wasn't it?" Humes asked. "Yes," Jenkins replied.

The trial is expected to resume today.