Dynalectron Corp. earnings fell last year but were second only to the record year in 1981, President Jorge Carnicero said yesterday.

Profits at the McLean firm were $13.1 million ($1.53 a share), compared with $13.9 million ($1.62) in 1981. Carnicero said that while that's a drop of 5 percent, the 1982 figures are 160 percent higher than any other year since the company started doing business in 1946.

Revenues slipped to $457.9 million from $475 million.

Fourth-quarter 1982 earnings were $3.97 million (47 cents), compared with $4.8 million (56 cents) in 1981. Revenues dipped to $121.6 million from $125.8 million.

Cerberonics Inc., a Northern Virginia firm that provides engineering, analytical and technical services to the U.S. government, posted a 165 percent increase in profits during its second quarter and took in as much in revenues as it did during the entire first half last year.

Earnings jumped to $321,000 (34 cents) from $121,000 (13 cents) in the comparable period of 1982. Revenues grew 94 percent to $6.3 million from $3.2 million.

For the half, Cerberonics earnings climbed 156 percent to $622,000 (66 cents) from $243,000 (26 cents) in 1982, while revenues increased to $10.7 million from $6.3 million.

Cerberonics officials said two significant aircraft material support contracts accounted for the dramatic gains.

Federal Realty Investment Trust posted 1982 profits of $3.4 million (80 cents), 26 percent higher than the 1981 figures of $2.7 million (67 cents), officials said yesterday.

Federal Realty said its net cash flow from operations set a record, growing 23 percent to $4.8 million from $3.9 million in 1981. The trust paid dividends of $1.02 per share, up 14 percent from the 89.5 cents paid the year before.

Revenues increased to $15.2 million from $14.4 million, the Chevy Chase trust reported. Federal Realty is a real estate investment trust that owns and operates shopping centers.

Profits at Isomet Corp., a Springfield firm that sells optical components of laser information handling systems, dropped by half to $453,000 (29 cents) in 1982 from $913,000 (60 cents) in 1981. Revenues slipped to $4.2 million from $4.3 million.

Isomet received new orders of $4.541 million in 1982, up only $1,000 from the year before.

Fourth-quarter profits fell to $112,000 (7 cents) on revenues of $1.2 million, compared with earnings of $130,000 (9 cents) on revenues of $1.1 million in 1981.

Another realty trust, Washington Real Estate Investment Trust, had net income of $4.9 million ($1.02) during 1982, compared with $4.5 million (95 cents) in 1981. Revenues increased to $14.7 million from $13.5 million.

Fourth-quarter earnings were $1.34 million (28 cents), compared with $1.32 million (27 cents) the year before, while revenues increased to $3.8 million from $3.5 million.

Second-quarter profits at Tech Serv Inc. dropped to $22,348 (4 cents) from $133,305 (23 cents) in the similar period of 1981. Revenues in the quarter ended Dec. 25 were $692,293, down from the $916,172 posted in 1981.

Tech Serv, a Beltsville company that builds and sells electronic control products and electromechanical systems, said it lost $63,972 in the latest six months, compared with earnings of $70,228 (12 cents) a year earlier. Revenues declined to $1.2 million from $1.5 million.

PHH Group Inc. said yesterday that revenues and earnings for the nine months ended Jan. 31 hit record levels. Profits increased 15 percent to $25.5 million ($1.61) from $22.2 million ($1.42), while revenues gained 22 percent to $420.1 million from $345.8 million.

In the third quarter, the Hunt Valley, Md., company had profits of $9 million (57 cents) on revenues of $144.8 million, compared with profits of $7.4 million (47 cents) on revenues of $114.1 million the year before.

Explaining the good performance, President Jerome Geckle said the Homequity subsidiary benefitted from the decline in interest rates in the mortgage market and sold more homes. Homequity sells homes for companies that transfer employes.

PHH is a diversified company that also is involved in car, truck and aircraft management and expense management programs.

Doughtie's Foods Inc. of Portsmouth said its earnings rose to $400,400 (48 cents) in 1982 from $299,400 (36 cents) in 1981 as sales reached a record $50 million, compared with $46.4 million the year before.

Profits in the fourth quarter were $108,400 (13 cents), compared with $48,600 (6 cents). Fourth-quarter sales also set a record, $12.8 million, compared with $12.3 million in the 1981 period. Doughtie's sells prepackaged foods, primarily meats, to institutions from distribution centers in Maryland, Virginia and North Carolina.