FCC Technician Exam Question Of The Day (T9B02)

Q) What is the impedance of the most commonly used coaxial cable in typical amateur radio installations?

A) 50 ohms

NJ2X Notes:
50-ohm coaxial cable is the de facto standard used in amateur radio applications.  It is important that all the elements in the chain have matching impedance (radio, feedline, antenna, ...).  If there is a mismatch of impedance, then SWR will be affected.