[TowerTalk] Fair rite materials for choke baluns

[Wes Attaway (N5WA)]

It is good to know that we can rely on #31 and #43 for many applications.

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Wes Attaway (N5WA)
(318) 393-3289 - Shreveport, LA
Computer/Cellphone Forensics
AttawayForensics.com
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-----Original Message-----
From: TowerTalk [mailto:towertalk-bounces at contesting.com] On Behalf Of Jim
Brown
Sent: Sunday, July 03, 2016 11:18 AM
To: towertalk at contesting.com
Subject: Re: [TowerTalk] Fair rite materials for choke baluns

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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