Qualstar Corp. narrowed its net loss and increased revenue in the fiscal fourth quarter as the company continues to execute its turnaround plan. The Westlake Village manufacturer of data tape storage and power supply products reported a net loss of $254,000 (-2 cents a share) for the quarter ending June 30, compared with a net loss of $677,000 (-6 cents) in the same period a year earlier. Revenue increased 18.5 percent to $3.2 million. Chief Executive Steven Bronson said he was pleased with the results that include lower operating expenses and product expansion in both the power supply and data tape storage markets. “This demonstrates that we are executing our turnaround plan,” Bronson said in a prepared statement. “We continue to explore other avenues to achieve further growth and continued momentum.” Shares closed up 1 cent, or nearly 1 percent, to $1.15 on the Nasdaq.