Product Overview
What it is: A hermetically sealed metal RF crystal filter module marked with NS logo, Part No. 726-062-002, and frequency marking 21.991-6 (interpreted as 21.991 MHz).
What it’s used for: Designed for intermediate frequency (IF) filtering in military communication systems, aviation radios, RF receivers, and secure signal processing equipment. Provides narrowband signal selection centered at 21.991 MHz for stable channel isolation.
