* The government sold $6.5 billion in 10-year notes yesterday at an average yield of 11.30 percent, slightly less than the previous sale but higher than expected.

There were $15.2 billion in tenders for the 11 1/4 percent coupon notes that sold at an average price of 99.705, with 100 the par, or face, value.

The yield was the lowest since the 10.16 percent yield on May 16, 1983. It was slightly less than the 11.36 percent of Feb. 15.

However, Dean Witter Reynolds Senior Vice President William V. Sullivan Jr. noted that the 10-year note had traded at 11.13 percent on a when-issued basis Tuesday. He said the higher payout on the auction reflected disappointment at Federal Reserve Chairman Paul A. Volcker's remarks to the Senate Banking Committee indicating that the Fed had not eased its policy.

Sullivan said the $15.2 billion "cover" also was lower than expected on this sale and signaled a muted retail interest in the note.

The auction was the second leg of the Treasury's second-quarter refunding, which will raise a record $20.5 billion.

On Tuesday, the Treasury sold $8.01 billion of three-year notes at an average yield of 10 percent, down from 10.40 percent at the previous sale of similar maturities in February.

Today, the Treasury is to sell $6 billion of 29 3/4-year bonds. Sullivan said this bond was trading at 11 3/8 percent on a when-issued basis late yesterday.