Federal Communications Commission Chairman Julius Genachowski was eager to talk about spectrum issues in a question-and-answer session before the Economic Club of Washington, but evaded questions about a proposed merger between AT&T and T-Mobile.

When asked about the Comcast-NBC Universal deal that the FCC approved this year, the chairman said that he has made it a policy not to talk about the merger review, saying only that it was important not to prejudge transactions and to follow a fair process.

Genachowski also revisited his defense of spectrum auctions, repeating his assertions that spectrum problems could damage the emerging mobile economy. He was specifically asked about the proposal to reallocate spectrum currently held by broadcasters.

“I have no doubt that if we ran this auction, we would free up a significant amount of over-the-air broadcast spectrum,” he said, adding that such an auction would result in more money for the government and a more vibrant broadcast industry.

Genachowski touched briefly on several other topics on the FCC’s radar, such as mobile payments.

When asked whether there should be a tax on Internet purchases, Genachowski said anything that discourages investment and private investment should be looked at extremely carefully. He said the FCC did not have open proceedings on mobile payments, but said that the government must “get it right” or the United States will fall behind other countries.