Maxcon Line Isolator
For coax fed
dipoles, verticals, beams, slopers, loops, windom,
OCF, and yagi antennas
Frequency: 1.8 - 30 MHz
Through-line impedance: 50-ohms (nominal)
Insertion loss: less than 0.2 dB at 60 MHz
Inductance 70 uH
Choking Impedance  
1539 Ohms at a Frequency of 3.5 Mhz
Power handling: 3kW
Load mismatch tolerance:  
up to  3:1 VSWR at 3KW
Connectors: PL-259
Many companies often call this item different names to make it difficult to compare the same item between companies. A line isolator is also called a common mode choke, a 1:1 balun, a 1:1 unun, a current balun/unun, a feed line current choke, and a 1:1 Guanilla balun/unun/choke. All these names are for the same item: a common mode current suppression device that works to suppress common mode current on the outside braid of your antenna feed line. The purpose of the common mode choke is to suppress or reduce the common mode current shared byall the wires in a cable of one or more wires. In the case of coax feed line, the center wire and inside of
the coaxial braid carry the RF signal current and the outside of the braid can carry common mode current if it is not choked at the antenna feed point. A choking impedance of 400 ohms or more should be used.
Adding a common mode choke, with sufficient choking impedance, at the antenna feed point will keep the RF signal on the antenna and off the feed line.

New and Improved with Higher Choking Impedance