Probably has nothing to do with his use, but 13.56 MHz and surrounding
frequencies on shortwave are the homes of many unlicensed CW beacons. Many
are "squarers."
Zack W9SZ
On Tue, Feb 2, 2021 at 8:52 AM Jim Lux <jim@...> wrote:
On 2/2/21 5:04 AM, brown.beard.2020@... wrote:
Hi All
Sorry if this is not the right place to ask. Feel free to point me to a
more suitable place for my questions.
I have an antenna connected to a 13.56MHz RF signal and would like to
add a ferrite core to the cable from the antenna to the device to filter
out any noise coming from the environment.
How do i determine the appropriate specs for the ferrite core?
That's the ISM frequencies just below the amateur radio 20 meter band,
so anything that works for 14 MHz (20m) will probably work just fine for
13.56 MHz.
In general, 31 mix is a good choice for HF - it's suitably lossy at
those frequencies. You might check out K9YC's choke cookbooks and other
writeups..
You're presumably at low power for something like a badge reader, so you
probably aren't as interested in low loss transmitter designs.
*RFI, Ferrites, and Common Mode Chokes For Hams
<>**Most recent update April
2019.*This tutorial is directed specifically to RFI in ham radio
applications. It includes an extended discussion of the use of common
mode chokes in antenna systems and for suppression of RFI. A chapter on
audio and computer interconnections in ham stations shows how to make
bulletproof connections between a computer sound card and ham rigs for
SSB, RTTY, PSK31, and SO2R contesting without expensive interface boxes,
using nothing more than simple cables with the right connectors on each
end. There's also a chapter on grounding and bonding.
This is a new applications note summarizing my work on *Chokes and
Transformers For Receiving Antennas.
<>**NEW!*October
2018
<>
Virus-free.
www.avg.com
<>
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