WHRB, Harvard's radio station, has been off the air since Thursday afternoon because of a transmitter failure and it is not known exactly when they will be back on the air," a WHRB spokesman said yesterday.

James S. Wolper '76, an announcer with WHRB, said yesterday that he discovered the transmitter failure about 12:30 p.m. Wednesday and station engineers have not been able to fix the problem.

The chief engineer at WHRB said yesterday that the cause of failure was that "the transmitter was old."

The engineer said, "We are trying as hard as possible, just about around the clock, and we will be back on the air as soon as possible."