HF Low Band Common Mode Choke 1.5kW
Intention to put anywhere along the coaxial cable to suppress common mode currents along the 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 one station cable to another station cable. Or the feedline parallels another feedline.
Common mode choke must be located outside of the station before unwanted currents get near station wiring.
Measured common mode choke isolation with HP8753ES Network Analyzer:
1.8 MHz = 2 kOhm
3.65 MHz = 12 kOhm
7.1 MHz = 1.8 kOhm
Max. power = 1.5 kW
Uses Teflon RG142 cable
Connectors SO239, PL259