Jim,
While I have reviewed your tutorial many times and there are some areas that
I may not yet totally understand, I do find that your standard comment of
"read the tutorial" is often less than helpful in clarifying a situation.
In this case in particular, I must admit that I thought the answer was the
other way around.
I have again reviewed the tutorial (Rev 6 Dec 2016) and found the paragraph
that does indeed repeat what you refer to. I thought that basically only the
material mattered, not the shape. So, if we are comparing #31 toroids to #31
Clamp-Ons, they are basically going to give about the same results.
You also "recommend" many Big #31 Clamp-on options for HF usage in your
cookbook. In fact, there are also other places in the tutorial where the
clamp-on chokes are discussed and yet none of the sections say that the
Clamp-On is a poor choice for usage at HF.
In reviewing Appendix 1, I cannot see how the #31 Big Clamp-On is a bad
choice. The first 4 Manufacturer's Published Data charts in Appendix 1 seem
to show about the same performance between circular and clamp on cores.
Comparing the 2.4" OD toroid against the Big #31 Clamp-On seem to provide
similar data.
#31 Toroid: Impedance/ESR - 5 turns (Dark red curve) peak at about 1,500
ohms
#31 Clamp-On: Impedance/ESR - 5 turns (Dark red curve) peaks at about 3,000
ohms
Here's another section where you certainly don't have anything bad to say
about Clamp-Ons.
The Big Clamp-Ons appear to be expensive but they're not - one is roughly
equivalent to three or
toroids! They are wonderful for portable and Field Day operations, because
you can easily apply
them to coax without taking the connector off. There is another advantage -
chokes for 160-40
meters using the Clamp-On weigh about a half pound less than one using
toroidal cores.
Color me confused. Where have I gone astray?
> Gerald, VE1DT
He's absolutely correct. Many times I've posted a link to my tutorial on the
topic. I spent years learning how this stuff works, and months writing it
up. I won't repeat it here. Only the link. k9yc.com/RFI-Ham.pdf
73, Jim K9YC
On Sun,6/18/2017 7:44 PM, john@kk9a.com wrote:
I was reading the recent QST article RF Mayhem by WB8IMY. The author said to
avoid using snap-on ferrites for problems caused by HF signals as they
rarely work well at HF. It is best to stick with circular cores.
Is this correct? I was not aware that snap-ons were less effective.
John KK9A
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