Garfinckel, Brooks Brothers, Miller & Rhoads, Inc., a major Washington-based retail conglomerate, yesterday reported a 73 percent increase in earnings and a 26 percent rise in sales for the first quarter of this year.

Net income for the period ended May 2 was $1.9 million (43 cents a share) compared with $1.1 million (25 cents). Net sales for the quarter were $117.7 million compared with $93.5 million during the first quarter last year.

"We are delighted to be able to report results which furnish such a satisfactory confirmation of the expectations we expressed at our annual meeting of shareholders earlier this week," said David R. Waters, chairman and chief executives officer of the firm.

Outlet Co., owner of WTOP radio in Washington, reported increased broadcasting earnings for the first quarter although the company as a whole reported a loss.

The net loss was $365,000 compared with a net loss of $1.99 million a year ago. Revenues were $31.1 million compared with $25.5 million in the first quarter last year.

Outlet's broadcastings division, including WTOP radio, had earnings of $4.8 million compared with $4.2 million and revenues of $17.3 million compared with $12.3 million.

Outlet also has a specialty stores division which showed a first quarter loss.

The company plans to "focus our strength on broadcasting and broadcast-related businesses, which have produced excellent growth and profitability for us," said Outlet President Bruce G. Sundlun.