Radio Shack PRO-83 - Manual (Page 13)

13 The Basics
setting up your scanner
Connecting the Antenna
To attach the supplied flexible antenna to the
connector on the top of your scanner, align the slots
around the antenna's connector with the tabs on the
scanner's BNC connector. Then slide the antenna's
connector down over the scanner's connector and
rotate the antenna connector's outer ring clockwise
until it locks into place.
Connecting an Optional Antenna
The scanner's BNC connector makes it easy to
connect a variety of optional antennas, including an
external mobile antenna or outdoor base station
antenna. Your local RadioShack store sells a wide
selection of antennas.