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#1
October 11th 05, 10:47 PM
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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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#2
October 11th 05, 11:45 PM
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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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#3
October 11th 05, 11:50 PM
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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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#4
October 12th 05, 12:10 AM
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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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#5
October 12th 05, 12:35 AM
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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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#6
October 12th 05, 01:22 PM
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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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#7
October 15th 05, 12:12 AM
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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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#8
October 15th 05, 02:35 PM
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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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#9
October 18th 05, 03:15 AM
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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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#10
October 18th 05, 10:09 AM
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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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