On Sun,7/3/2016 7:55 AM, Rudy Bakalov via TowerTalk wrote:
So, what am I missing?
The fundamental principles upon which ferrite chokes work.
Why is 52 rarely mentioned and the debate is usually 31 vs 43?
Quoting from the Fair-Rite engineering catalog, #52 is "a new high
frequency NiZn ferrite material that combines a high saturation flux
density and a high Curie temperature. SM beads, PC beads, and a range of
rod cores are available in this material."
Someone asked this question several months ago, so I studied that catalog.
A thorough search found only very small circuit board components with
that material, components that are much too small to fit coax.
Does it make sense to build a "universal" choke using 2 or 3 different cores to
cover the entire 160 to 10 m range?
No. What DOES make sense is multiple chokes in series along a cable to
cover a wide frequency range, each "tuned" to specific parts of that range.
Study k9yc.com/RFI-Ham.pdf for an complete theoretical development of
how chokes work, AND measured data that supports and is the basis for
that development. I first published this material as an Audio
Engineering Society Paper in 2005, and extended it to the ham world in
2007. This particular applications note/tutorial has had more than 2
million downloads from my website, and key elements have been added to
the ARRL Handbook.
In all of my scientific writing (and I've done a lot), I've always cited
the work of others on whom my work is based, or who have contributed to
the topic. When someone sent me a link to W1HIS's work, I studied it,
and cited it. I continue to be disappointed that ten years after my
first publication, G3TXQ has yet to cite my work, which is the clear
basis for his.
A primary reason for my focus on #31 material (and I am the guy who not
only showed Fair-Rite that their new #31 was a useful HF material with
that 2005 AES Paper, but also introduced it to the ham world), is that
#31 is the universally useful material for use in building common mode
chokes between the AM broadcast band and VHF. It is the BEST material
below 5 MHz, and nearly as good as #43 ABOVE 10 MHz. This universality
allows us as hams to buy in quantity, taking advantage of quantity price
discounts from industrial vendors, and escaping the predatory high
prices of ham vendors who sell at 2-4X these quantity prices.
73, Jim K9YC
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