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Old October 11th 05, 10:47 PM
Jeff
 
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Default Choice of iron powder toriod?

Hi,
Im confused regarding the choice of iron powder toroid for a 7Mhz high pass
filter. I need to use a small size (T68) toroid. For the freq range, some
reference texts say T68-2 is the one, others say T68-6" grade. I see
differing "best Q range" specs for the 6
grade.....2-30Mhz......10-50Mhz...etc.
Have similar need for 20Mhz LPF, but assume "6" is really the choice there.
Any suggestions as to the relative differences and reasons to choose between
grades 2 and 6 for the HPF in T68 size?
Thanks,
JEFF


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Old October 11th 05, 11:45 PM
Tim Wescott
 
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Jeff wrote:

Hi,
Im confused regarding the choice of iron powder toroid for a 7Mhz high pass
filter. I need to use a small size (T68) toroid. For the freq range, some
reference texts say T68-2 is the one, others say T68-6" grade. I see
differing "best Q range" specs for the 6
grade.....2-30Mhz......10-50Mhz...etc.
Have similar need for 20Mhz LPF, but assume "6" is really the choice there.
Any suggestions as to the relative differences and reasons to choose between
grades 2 and 6 for the HPF in T68 size?
Thanks,
JEFF


As far as I know, 7MHz is on the border between using one mix or the
other. You'll see different Q's because details of winding, wire choice
and mounting will affect Q, as would use of a core from another
manufacturer (I don't know if anyone other than MicroMetals uses that
system, but if they did I wouldn't count on it being standardized).

If you're not going to be hitting it with really high power and if you
don't need it to be highly resonant I wouldn't worry too much. If
you're going for an engineered solution then you should make a number of
"identical" coils and test them; just make sure that the coils you make
are representative of what you'll be manufacturing.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com
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Old October 11th 05, 11:50 PM
Joe L.
 
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In article ,
"Jeff" wrote:

Im confused regarding the choice of iron powder toroid for a 7Mhz high pass
filter. I need to use a small size (T68) toroid. For the freq range, some
reference texts say T68-2 is the one, others say T68-6" grade. I see
differing "best Q range" specs for the 6
grade.....2-30Mhz......10-50Mhz...etc.
Have similar need for 20Mhz LPF, but assume "6" is really the choice there.
Any suggestions as to the relative differences and reasons to choose between
grades 2 and 6 for the HPF in T68 size?


Either grade 2 or 6 should work fine at 7 and 14 MHz. The Al values
differ somewhat, so the number of turns to get a given inductance will
be a little higher for grade 6 than grade 2. You only need to confirm
that the number of turns required will actually fit on your T68-size
core.

For a given number of turns, the unloaded Q does peak at one frequency
but is still quite good on either side of that frequency. Unless you
have some real need to achieve the highest possible Q for a given
inductance at the frequency of interest, I wouldn't worry too much about
it. Wind the toroids, build the filter, and see how it works out!

--
Joe
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Old October 12th 05, 12:10 AM
Pooh Bear
 
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Jeff wrote:

Hi,
Im confused regarding the choice of iron powder toroid for a 7Mhz high pass
filter. I need to use a small size (T68) toroid. For the freq range, some
reference texts say T68-2 is the one, others say T68-6" grade. I see
differing "best Q range" specs for the 6
grade.....2-30Mhz......10-50Mhz...etc.
Have similar need for 20Mhz LPF, but assume "6" is really the choice there.
Any suggestions as to the relative differences and reasons to choose between
grades 2 and 6 for the HPF in T68 size?


Having just been playing with Micrometals cores myself, I gather that -2 is
indeed the 'best' for higher frequencies.

The local distributor says it's stocked in greater depth too.

Have you also looked at Magnetics Inc and Arnold ?

Graham

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Old October 12th 05, 12:35 AM
Joerg
 
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Hello Jeff, wrote:

Hi,
Im confused regarding the choice of iron powder toroid for a 7Mhz high pass
filter. I need to use a small size (T68) toroid. For the freq range, some
reference texts say T68-2 is the one, others say T68-6" grade. I see
differing "best Q range" specs for the 6
grade.....2-30Mhz......10-50Mhz...etc.
Have similar need for 20Mhz LPF, but assume "6" is really the choice there.
Any suggestions as to the relative differences and reasons to choose between
grades 2 and 6 for the HPF in T68 size?


Not that this is an exact science but typically I switch from #2 to #6
around 10MHz. But I never design with high Q because that can be a pain
in production.

Regards, Joerg

http://www.analogconsultants.com


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Old October 12th 05, 01:22 PM
William E. Sabin
 
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Get a copy of Amidon's catalog which gives detailed suggestions for powdered
iron and ferrite materials, based on many years of experience.
www.amidoncorp.com

Bill W0IYH

"Jeff" wrote in message
...
Hi,
Im confused regarding the choice of iron powder toroid for a 7Mhz high
pass
filter. I need to use a small size (T68) toroid. For the freq range, some
reference texts say T68-2 is the one, others say T68-6" grade. I see
differing "best Q range" specs for the 6
grade.....2-30Mhz......10-50Mhz...etc.
Have similar need for 20Mhz LPF, but assume "6" is really the choice
there.
Any suggestions as to the relative differences and reasons to choose
between
grades 2 and 6 for the HPF in T68 size?
Thanks,
JEFF




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Old October 15th 05, 12:12 AM
Joerg
 
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Hello William,

Get a copy of Amidon's catalog which gives detailed suggestions for powdered
iron and ferrite materials, based on many years of experience.
www.amidoncorp.com


Absolutely. I literally wore one of those catalogs to the point where
you could see through several pages.

Then there are the ARRL Handbook and their Antenna Book. Both well worth
every penny.

Regards, Joerg

http://www.analogconsultants.com
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Old October 15th 05, 02:35 PM
William E. Sabin
 
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Hello Joerg, nice to meet you for the first time.

Bill W0IYH

"Joerg" wrote in message
...
Hello William,

Get a copy of Amidon's catalog which gives detailed suggestions for
powdered iron and ferrite materials, based on many years of experience.
www.amidoncorp.com


Absolutely. I literally wore one of those catalogs to the point where you
could see through several pages.

Then there are the ARRL Handbook and their Antenna Book. Both well worth
every penny.

Regards, Joerg

http://www.analogconsultants.com



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Old October 18th 05, 03:15 AM
Joerg
 
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Default Choice of iron powder toriod?

Hello Bill,

Hello Joerg, nice to meet you for the first time.


Likewise. You name sounds very familiar, IIRC from a book about design
of HF gear. Didn't you work at Collins in the good old days when they
had mechanical filters in their gear?

Regards, Joerg

http://www.analogconsultants.com
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Old October 18th 05, 10:09 AM
William E. Sabin
 
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Default Choice of iron powder toriod?

Yes. I started at Collins Radio engineering department in 1964 and retired
from Rockwell Collins in 1990. For more info search Google for my name and
my call sign. See QRZ.COM for W0IYH. See www.noblepub.com.

Bill W0IYH

"Joerg" wrote in message
t...
Hello Bill,

Hello Joerg, nice to meet you for the first time.


Likewise. You name sounds very familiar, IIRC from a book about design of
HF gear. Didn't you work at Collins in the good old days when they had
mechanical filters in their gear?

Regards, Joerg

http://www.analogconsultants.com





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