Plans to construct a new radio telescope, perhaps as large as 250 feet in diameter, were disclosed recently by the National Aeronautics and Space Administration to the Senate Aeronautical and Space Science Committee. A request for funds to start construction of the facility, to be located at Goldstone, Calif., was included in a tentative NASA budget drafted for the coming fiscal year. Intended as a principal station for communication with satellites and space probes, it has been proposed that the instrument be built as part of a deep-space network to include two other radio telescopes now under construction in Australia and in South Africa.