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What is RFI choke?
The CHA RFI CHOKE will prevent, greatly reduce, or totally eliminate common-mode current (which can cause RFI) carried by the coax cable. They can be installed either at the antenna feed point or right behind the antenna tuner.The choke is composed of the following: 1 X 12″ RG-8X. 5 X Snap-On core (#31 Ferrite Mix)
What is a ferrite core used for?
Ferrite beads and cores are used in equipment design to suppress and dissipate high frequency noise levels caused by electromagnetic devices. Ferrite components are used to attenuate EMI and can be extremely effective. Of course, using properly installed and grounded shielded cables helps suppress EMIs.
How are ferrite cores used for cable suppression?
Ferrite cores (chokes) provide an inexpensive, and effective, way of coupling high-frequency resistance into a cable in order to reduce the common-mode current, and hence the radiation (or pickup) from the cable.
Are there any low frequency ferrite chokes for cable suppression?
For low-frequency cable emission problems, typically below 10 MHz, ferrite chokes have not been very useful, since their impedance is too low, at these frequencies, to be effective. I have always wished for a similar, simple low-frequency solution to cable emission/susceptibility problems. My wish finally has been granted.
What kind of resistor is a ferrite choke?
Basically ferrites can be thought of as high-frequency resistors, with little or no impedance at low-frequencies or dc. Ferrite cores are most effective in providing attenuation of unwanted noise signals above 10 MHz. The figure below shows a ferrite choke on a USB cable.
How is the impedance of ferrite cores increased?
The impedance of ferrite cores can be further increased by using multiple turns. However, this also increases the inter-winding capacitance and degrades the high-frequency performance of the choke.