Dynalectron Corp., a diversified technological services and energy reserch firm based in McLean, reported record sales and profits for the fourth quarter and year ended Dec. 31.

In the recent three months, Dynalectron's profits increased to $2.59 million compared with $2.47 million a year earlier, as sales rose 20 percent to $125 million. Per-share profits were 31 cents vs. 34 cents, because there were more shares or equivalent shares outstanding in 1980.

For the year, profits were up 25 percent to $5 million (65 cents a share) from the prior record of $4 million (57 cents) in 1979.Sales also rose 25 percent to $442.6 million.

Chairman Jorge Carnicero also noted that stockholders' equity in Dynalectron rose to $56 million ($6.62 a share) from $36 million ($5.09). The company sold 1.1 million new shares of common stock last October.

Directors approved a cash dividend of 10 cents a share, payable April 17 to owners of record March 31. The payout is up 25 percent from last year, Carnicero said.

E.c. eRnst Inc. reported an operating loss of $341,000 in the three months ended Dec. 31 on contract income of $9.1 million. Including a one-time gain of $850,000 (a payment from L.K. Comstock & Co., related to previous income tax returns that had included Comstock as a subsidiary before it was divested), net income was $509.000. Comparable results for the previous year were not available from the Washington electrical contracting company, which is being reorganized under federal bankruptcy laws.

For the nine months ended Dec. 31, net income was $14.1 million compared with a loss of $4.2 million, with operating earnings in the 1980 period of $1.4 million and extraordinary gains of $12.7 million.Contact income fell to $40 million from $50.6 million. Chairman Joseph Griffin noted yesterday that contract income exceeded costs in the recent quarter for the second consecutive period.

LogEtronics Inc. said earnings increased 15 percent in 1980 to $1.43 million ($1.32 a share) from $1.24 million ($1.17) the previous year as sales rose 8 percent to $30.6 million.