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Receiving LWBC in North America

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NJQA:

--- Quote from: circuitmike on February 27, 2022, 2000 UTC --- I should probably invest in a few more ferrite toroids and the like. There's still so much noise coming out of my house! And I do have an AM BCB filter around here somewhere, so I'll experiment with putting that in line.

--- End quote ---

Be sure to use ferrites with the right mix!  Mix type 75 or 77 is what you should be using.  You can get them at DXEngineering.

I also have all of the connections to my KiwiSDR going through Type 77 ferrite cores - antenna, GPS, ethernet, and power.  Each has two cores glued together, and then wrapped in fiberglass cloth tape (the tape helps protect the ferrites from chipping).

The purpose of the LPF is to ensure that strong out of band signals on the BCB or SW don’t drive the receiver into compression.

The KiwiSDR is a very capable LW receiver.

~SIGINT~:
Here is my "cheat sheet" on ferrite materiels.

Materiel Types
There are two basic ferrite material groups:

 (1) Those having a permeability range from 20 to 850 µ are of the Nickel Zinc (NiZn) class (mix 43, 52, 61); and

 (2) Those having initial permeabilities above 850 µ are usually of the Manganese Zinc (MnZn) class (Mix 31, 73, 75)

The Nickel-zinc (NiZn) ferrite cores (mix 43, 52, 61) have low permeability and exhibit high volume resistivity. Nickel-zinc ferrites have a higher resistivity and are used at frequencies from 2 MHz to several hundred megahertz.

The Manganese-zinc (MnZn) ferrite cores (Mix 31, 73, 75) have high permeabilities above 800 µ, have fairly low volume resistivity and moderate saturation flux density. They offer high 'Q' factors for the 1 KHz to 1 MHz
frequency range.

These cores are also very useful for the attenuation of unwanted RF noise signals in the frequency range of
2 MHz to 250 MHz.

MIX 31 -> 1 MHz - 300 MHz, good for HF
MIX 75/J -> 150 KHz - 10 MHz

circuitmike:
Thanks for the ferrite primer! I've been meaning to build some ferrite rod antennas, and maybe a ferrite sleeve loop at some point. I have some 200 mm rods, including some that are 30 mm thick or so which are MnZn of an unknown mix. I'm curious how well those will perform on longwave. I might stick them end-to-end inside a piece of ABS pipe and see if I can make a giganto-ferrite rod!

~SIGINT~:
Here are some interesting build your own articles for you.

Giuseppe’s homebrew rotating ferrite antenna
https://swling.com/blog/2021/01/giuseppes-homebrew-rotating-ferrite-antenna/

Giuseppe discovers his homebrew rotating ferrite antenna works amazingly indoors and nulls RFI
https://swling.com/blog/2021/01/giuseppe-discovers-his-homebrew-rotating-ferrite-antenna-works-amazingly-indoors-and-nulls-rfi/

Giuseppe’s Homebrew “TFerrite 2” Mediumwave & Shortwave Antenna
https://swling.com/blog/2021/09/giuseppes-homebrew-tferrite-2-mediumwave-shortwave-antenna/

Guest Post: Pavel’s Homebrew “Monster” Drain Pipe FSL Antenna
https://swling.com/blog/2021/12/guest-post-pavels-homebrew-monster-drain-pipe-fsl-antenna/

RobRich:
I have not bothered much with LW BCB in quite awhile, but I used to often hear Medi 1 (1.6MW!) out of Morocco at night using my Kenwood R-2000 and 148' LoG antenna. The other usual LW BCBs were occasionally noted, but admittedly they were largely hit or miss in comparison.

My old LoG uses a "shielded" coaxial design, so differential currents should be relatively balanced and common mode currents somewhat mitigated, thus I do not bother with a balun or impedance matching transformer at the feedpoint. There are few snap-on chokes of whatever mix I had in the parts box at the time, so even those are highly suspect at such low frequencies.

I do have KD9SV common mode chokes near the input of some of my receivers, and I suspect the design is mix 7x due to being optimized for lower HF.

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