Penril Corp. of Rockville reported yesterday that its earnings for the first nine months of the year climbed 22 percent to $1.32 million ($1 a share) from $1.07 million (82 cents) in the same period a year ago.

The Montgomery County electronics maker said revenues for the period jumped 50 percent to $24.5 million from $16.2 million, and sales for the latest quarter were up 33 percent to $8.4 million from $6.4 million.

Despite the strong sales gain, third-quarter earnings were up only a little to $447,000 (33 cents) from $421,000 (32 cents), the company said.

Another Rockville electronics firm, Microdyne Corp. reported at 49 precent increase in earnings for the first six months of its year, attributing the gain to the acquisition of Antennas For Communications Inc.

In its first report since the two companies merged, Microdyne said its operating income for the first half increased to $1.66 million (60 cents per share) from $1.11 million (48 cents) in the same period a year ago. After using income tax credits for previous losses by AFC, Microdyne showed a net for the six months of $1.2 million (52 cents).

Sales of the combined companies totalled just over $11 million for the six months ended May 4, up from $7.7 million a year earlier.

For the second quarter, Microdyne earned $863,000 (31 cents) versus $658,000 (29 cents) on sales of $5.7 million, up from $4.1 million.

Virginia Electric and Power Co. said its common stock earnings per share fell to $1.60 for the 12 months ended May 30 from $1.74 in the same period a year ago. Actual commonstock earnings increased slightly to $144.6 million frm $143.5 million, but earnings per share fell because the company has issued almost 8 million additional shares.

Vepco's total income, including dividends on preferred stock, was just over $200 million for the 12 months, up from $198.4 million a year earlier.

Also reporting from Richmond, Owens, Minor & Bodeker Inc. said previously announced profits for the fiscal year ended Marck 31 were under-stated because of accounting errors.

The company said it earned $1.59 million ($2.06 per share) rather than the previously reported $1.35 million ($1.74) for the year, based on last-in, first-out accounting. The company recently switched from first-in, first-out, accounting, producing large adjustments in reported profits.