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Author Topic: RFI choke - alternative/DIY solution  (Read 4054 times)
HS0ZIB
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Posts: 435




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« on: July 06, 2014, 12:31:03 AM »

I've been re-installing my screwdriver antenna and bonding the various parts of my vehicle together.  These actions have substantially improved the performance of the antenna and reduced the QRN levels.

But I still have broadband QRN from the car on-board computers.  The recommended solution is to install snap-on toroids around the various cables that are attached to the computer unit, as well as on the DC power cables of my rig.

Here is the problem - it is all but impossible to purchase RFI toroids in Thailand.  I can order them from overseas, but the cost will be expensive, the customs tax will increase that cost and there is a high risk that the Thai postal service will lose the package in transit.

Is there a 'poor man's solution' to this, whereby I can use some locally-sourced and common electronic components to achieve the same result as the RFI choke toroids?
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K0BG
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« Reply #1 on: July 06, 2014, 12:57:36 PM »

In a word, no.

Ferrites are interesting material. If you want to know how they work, read this: http://www.k0bg.com/beads.html

By the way, single turn chokes just don't suppress RFI to any level detectable. Like any good choke, they require multiple turns to be effective. At a minimum, make sure you have the common mode choked off the coax and control lines to your antenna. This keeps the lines from being part of the antenna, and picking up most of the RFI the on-board electronics generate.
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