Vance Street Capital on Monday said it made another tech acquisition to beef up a portfolio company.

The West L.A. private equity firm announced it had closed on the purchase of Lark Engineering, a San Juan Capistrano designer and manufacturer of radio frequency filters for commercial, industrial and military uses. RF filters are used in telecommunications systems.

Lark becomes a division of Secure Communication Systems, a Santa Ana maker of specialty computing systems, encryption equipment and other communications products for defense and industrial uses. Vance Street acquired that business 2009.

Terms of the Lark deal were not disclosed, but Vance Street said Fifth Third Bank provided the debt financing.

This is Vance Street’s second add-on acquisition for Secure Communication. In May it acquired Smart Electronics, an Anaheim provider of electronic circuit boards, sub-assemblies and other components for defense and aerospace products.