#2 powdered iron at mu of 10 is the lowest mu of the powdered iron types
listed with a frequency range that covers 160 meters (in some lists #2 is
2-30). You can rest assured Jerry Sevick had the list below. In his 160
meter comparison with #2 material, he tested 1,3,15 and 26. Number 6 really
doesn't work under 10 MHz, as specified in other lists. It's a "replaced"
mix that has had problems. Here's a composite list of powdered iron
materials from various incomplete sources.
0 Mix (Tan) 100-300 MHz u=1
1 Mix (Blue) 0.5-5 Mhz u=20
*2 Mix* (Red) 1-30 MHz, high volume resist. u=10 [Alt list 2-30 Mhz]
3 Mix (Gray) .05-.5 MHz, u=35
*6 Mix* (Yellow) 1-50 MHz, similar to mix #2. u=8 [alt list 10-50 MHz, alt
list use #8]
7 Mix 3-35 MHz, u=9 small cores only
*8 Mix *(Yellow / Red) 1-50 MHz, replaces 6 mix. u=35
10 Mix 30-100 MHz, u=6
12 Mix 50-200 MHz, u=4
15 Mix 0.1-2 MHz, u=25
*17 Mix* (Blue/Yellow) 50-200 MHz, good Q. u=3 [alt list u=4]
*18 Mix* (Green/Red) u=55, Low Core Loss, Similar to 8 Mix
*26 Mix* (Yellow/White) DC-800 KHz, great 60 Hz.
EMI range. Line 'em up on speakers / AC wires u=75
*40 Mix* (Green/Yellow) Power conversion similar to mix 26
*52 Mix* (Green/Blue) DC-1 MHz, high perm. u=75
73, Guy.
On Thu, Dec 15, 2011 at 10:50 PM, ZR <zr@jeremy.mv.com> wrote:
>
> ----- Original Message ----- From: "Guy Olinger K2AV" <
> olinger@bellsouth.net>
> To: <richard@karlquist.com>
> Cc: <topband@contesting.com>; "Martin" <hamradio@vr-web.de>
> Sent: Thursday, December 15, 2011 10:05 PM
>
> Subject: Re: Topband: T-200 vs. T-300
>
>
> Hi Rick,
>>
>> No magic. Just the right stuff, for the FCP, anyway.
>>
>> To your particulars, when Jerry Sevick measured various ferrites, he
>> measured the lowest loss at mu=40. This was very low, as was the #2
>> powdered iron at mu=10, the lowest of the powdered iron formulas.
>>
>
> Since when is a 2 mix the lowest mu? It is ideal for QRO and HF since 6
> and 7 mix arent made in QRO sizes and arent suitable at 160 anyway.
>
> Carl
> KM1H
>
>
>
>
> So use
>
>> of ferrites introduces a significantly reduced number of turns, with a
>> much
>> more coarse granularity of possible inductive values, that has to be
>> worked
>> out to use with the FCP, AND the behavior of the mu=40 core under highly
>> reactive loads is not spec'd by the manufacturer. The ferrite will have
>> far
>> less radiating surface if it does heat up under extreme reactive load, AND
>> the length of the parallel bifilar wires may not be enough to cover 160
>> with the needed behavior in this app.
>>
>> But my admonition about no ferrites has more to do with my knowing that
>> people have misc T240 and T200 form factor ferrites of ALL KINDS laying
>> around, and want to use the one they just found down in the junk box,
>> which
>> does NOT have the material # or mu marked on it anywhere. And these
>> requests seem to pop up just before a contest, when most hope of getting
>> the correct stuff before contest has gone by the wayside. You will note
>> that I have pounded in Amidon T300A-2 #2 powdered iron toroid or strict
>> equivalent, over and over again. And I get back "please, please, please
>> tell me that I can use my junkbox ferrite toroid". But don't hold your
>> breath. In over four years of working with non-resonant antenna solutions
>> on 160, **NONE** of the ferrites we tried to use made it. We burnt or
>> cracked ALL of them at QRO. ALL of them. Really. Ferrite demolition
>> derby.
>>
>> I have a new collection of #31 ferrite stuff, but I use those in low band
>> RFI suppression, not transformers. So I'm NOT going to tell anyone it's
>> OK
>> to use a ferrite toroid for feeding an FCP.
>>
>> Beyond that, what is NOT in doubt is that the #2 powdered iron choice
>> works
>> and works well. The installations where I have been able to run QRO brick
>> on key and quick go check toroid temp have all been stone cold. Anyone
>> has
>> contrary experience please let us know ASAP. We will certainly want to
>> investigate and determine why in one place and why not in another.
>>
>> As to why he made his #2 powdered iron choice, Jerry Sevick W2FMI, covers
>> this convincingly in his book, pages 58-63, which I will NOT try to
>> reproduce on the reflector, as even if I did, I can't pass along the
>> essential graphs, photos and diagrams. ("Understanding, Building, and
>> Using Baluns and Ununs -- Theory and Practical Designs for the
>> Experimenter", Jerry Sevick W2FMI, Copyright 2003, CQ Communications,
>> Inc.,
>> Hicksville, New York)
>>
>> I have found, over the time that I have been working on top-band issues,
>> that dropping back after blowing something up and consulting W2FMI or his
>> material has been most valuable.
>>
>> Alas, Jerry is a silent key, and I can no longer phone him to further
>> expound upon his choices. He particularly chose the large #2 powdered
>> iron
>> cores for applications with a lot of stress on the core, particularly 160
>> meters. Some key quotes:
>>
>> "Because my simple loss measurements indicated that the higher
>> permeability
>> powdered-irons had more loss than the No. 2 material, I decided to design
>> a
>> 4:1 Ruthroff Balun using this material--but with a larger core and more
>> turns than the McCoy Balun. Although McCoy's design has enjoyed
>> considerable success over the years, I felt that a larger inductive
>> reactance was desirable in order to assure better performance on the lower
>> frequency bands (particularly 160 meters). [Ibid p.59]
>>
>> "I knew ... that loss with ferrite materials was related to the voltage
>> drop along the length of the [bifilar winding] and to the ...
>> permeability.
>> Permeabilities of 40 (No. 67 Ferrite) exhibited the lowest loss. ...
>> powdered iron #2 material with a permeability of 10 also showed the very
>> same low loss. Because powdered-iron material has been known to be more
>> rugged and linear than ferrite material, this suggested that other
>> powdered-irons ... should be investigated. ... However all four materials
>> showed a definite lower input impedance than #2 material, ..." [Ibid
>> p.59]
>>
>> Sevick had access to all of the ferrites, but did not choose any of them
>> for his monster hang-on-the-back-of-the-tuner 4:1 Balun, especially
>> intended to deal with wild voltages, very reactive loads, etc, and handle
>> them as well on 160 as 80-10. Instead Sevick chose the T400A-2 and #2
>> powdered iron to lay out there as his personal method. So we've done the
>> same. And everywhere we've used teflon-sleeved #14 double polyimide on
>> the
>> #2 powdered iron cores, bad stuff has just quit happening, they work, and
>> they run stone cold.
>>
>> At various scattered places in the book Sevick talks about all the issues
>> that come to bear on designing an isolation transformer on 160 meters. I
>> may not be able to develop a federal level proof case satisfactory so
>> some,
>> but I am sticking with Mr. Sevick. His guidance has always panned out and
>> explained what was ailing. He did his high-stress 160 meter windings on
>> large #2 powdered iron toroids after research. So are we. We have the
>> hard-won results that prove out Sevick's and our choices.
>>
>> 73, Guy.
>>
>> On Thu, Dec 15, 2011 at 2:58 PM, Rick Karlquist <richard@karlquist.com
>> >wrote:
>>
>> Guy Olinger K2AV wrote:
>>>
>>> > Martin has the right instincts, says it feels fishy for this. But it's
>>> > worse than he thinks. And don't even consider using ferrites.
>>> >
>>> > The T300A-2 core and 20 bifilar turns were SPECIFICALLY chosen to >
>>> produce
>>> > a
>>> > residual inductance value in the right order of magnitude to cancel a
>>> > typical residual capacitive reactance from a 160 meter 5/16 wave single
>>> > wire folded counterpoise, AND provide enough coupling to make the
>>> > transformer work, AND maintain a low enough loss to operate QRO without
>>> > heating, or especially to operate QRP without further handicapping the
>>> > operator with needless loss. This allows the builder of the "simple
>>> > solution" to prune the wire to get resonance and remain somewhere >
>>> around
>>>
>>> I'm trying to understand here what is magic about powdered iron.
>>>
>>> It is true you can't just use any random piece of ferrite.
>>> But if the T300A-2 were replaced with LOW PERMEABILITY ferrite
>>> having the same permeability as a T300A-2 core, it would produce
>>> the required residual inductance. The loss of low permeability
>>> ferrite is extremely low, probably lower than powdered iron.
>>> Coupling is a function of how the turns are wound, not the core material.
>>>
>>> Am I missing something?
>>>
>>> Rick N6RK
>>>
>>>
>>>
>>>
>>> ______________________________**_________________
>> UR RST IS ... ... ..9 QSB QSB - hw? BK
>>
>>
>> -----
>>
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>>
>
_______________________________________________
UR RST IS ... ... ..9 QSB QSB - hw? BK
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