Low Band Common Mode Choke

Low Band Common Mode Choke


Low Band Common Mode Choke

SKU: 2989 Category:

Low Band Common Mode Choke – current balun 3.5 kW

Current balun or choke balun “isolates” common mode path along a feedline.

In transmitting antenna systems common mode currents harm antenna efficiency, lower gain, alter antenna pattern, and increase local RFI.
In receiving systems increases noise floor, distorts audio, causes computer crashes, or might cause RF burns.
Good common mode choke or current balun have high common mode impedance.
The combination of proper grounding and high common mode impedance can reduce unwanted currents to unnoticeable values.
Rule-of-thumb suggests a common mode impedance of 500 Ohm for 50 Ohm transmission lines. We suggest 1 kOhm or more.
Common mode chokes are necessary when using bandpass filters in a Multi-Multi station environment.


To prevent common mode currents from flowing from one station cable to another station cable. Or the feedline parallels another feedline.
Common mode choke must be located outside the station before unwanted currents get near station wiring.

Measured common mode choke isolation with HP8753ES Network Analyzer:
1.8 MHz = 650 Ohm
3.65 MHz = 3 kOhm
7.1 MHz = 2 kOhm
14.1 MHz = 750 Ohm
Max. power = 3.5 kW
Used RG142 Teflon coaxial cable
Connectors SO239 Outdoor mounting


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