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Wanted: bandpass filter design
Hi all,
I need a simple design for a BPF with a centre frequency of 17.2Mhz., corner frequencies one Meg or therabouts either side of that and a reasonably good shape factor (nothing critical here). I don't mind having to do a bit of tweaking of values myself if anyone has something close to that they can post. Passive L/C combinations only, please. (assume the usual 50R nominal Zs.) Thanks, p. -- The BBC: Licensed at public expense to spread lies. |
Paul:
[snip] I need a simple design for a BPF with a centre frequency of 17.2Mhz., corner frequencies one Meg or therabouts either side of that and a reasonably good shape factor (nothing critical here). I don't mind having to do a bit of tweaking of values myself if anyone has something close to that they can post. Passive L/C combinations only, please. (assume the usual 50R nominal Zs.) [snip] Such a design can be achieved with a vert simple formula and a pocket calculator or slide rule. Why don't you just use Bennett's simple formula for the maximally flat approximation all pole element values, or Takashi's simple formulae for the equiripple approximation all pole element values? Oh... perhaps you want elliptic [Cauer or Darlington] designs or perhaps a completely general parameter design in that case ypu will need a computer and will need to do some programming or buy some programming, or better yet... Hire a consultant... :-) Hey, I've designed literally thousands of LC filters over decades in most frequency ranges, for clients who have paid me well. I have access to very sophisticated and comprehensive general parameter LC filter design programs that I have written [In Fortran BTW] over lo these many years and they are immediately at my disposal. But... unfortunately for some... I never design filters for free! I'll do it for you at my usual consulting rates. My rates are reasonable. Just call or email me to discuss the terms and conditions. :-) -- Peter Professional Consultant - Signal Processing and Analog Electronics Indialantic By-the-Sea, FL peter dot brackett at "eye" triple "e" dot org. USA area code three two one, number seven two three, nine two five five. "Paul Burridge" wrote in message ... Hi all, I need a simple design for a BPF with a centre frequency of 17.2Mhz., corner frequencies one Meg or therabouts either side of that and a reasonably good shape factor (nothing critical here). I don't mind having to do a bit of tweaking of values myself if anyone has something close to that they can post. Passive L/C combinations only, please. (assume the usual 50R nominal Zs.) Thanks, p. -- The BBC: Licensed at public expense to spread lies. |
Paul:
[snip] I need a simple design for a BPF with a centre frequency of 17.2Mhz., corner frequencies one Meg or therabouts either side of that and a reasonably good shape factor (nothing critical here). I don't mind having to do a bit of tweaking of values myself if anyone has something close to that they can post. Passive L/C combinations only, please. (assume the usual 50R nominal Zs.) [snip] Such a design can be achieved with a vert simple formula and a pocket calculator or slide rule. Why don't you just use Bennett's simple formula for the maximally flat approximation all pole element values, or Takashi's simple formulae for the equiripple approximation all pole element values? Oh... perhaps you want elliptic [Cauer or Darlington] designs or perhaps a completely general parameter design in that case ypu will need a computer and will need to do some programming or buy some programming, or better yet... Hire a consultant... :-) Hey, I've designed literally thousands of LC filters over decades in most frequency ranges, for clients who have paid me well. I have access to very sophisticated and comprehensive general parameter LC filter design programs that I have written [In Fortran BTW] over lo these many years and they are immediately at my disposal. But... unfortunately for some... I never design filters for free! I'll do it for you at my usual consulting rates. My rates are reasonable. Just call or email me to discuss the terms and conditions. :-) -- Peter Professional Consultant - Signal Processing and Analog Electronics Indialantic By-the-Sea, FL peter dot brackett at "eye" triple "e" dot org. USA area code three two one, number seven two three, nine two five five. "Paul Burridge" wrote in message ... Hi all, I need a simple design for a BPF with a centre frequency of 17.2Mhz., corner frequencies one Meg or therabouts either side of that and a reasonably good shape factor (nothing critical here). I don't mind having to do a bit of tweaking of values myself if anyone has something close to that they can post. Passive L/C combinations only, please. (assume the usual 50R nominal Zs.) Thanks, p. -- The BBC: Licensed at public expense to spread lies. |
Conversely, go to the WB6BLD website and download the free student version
of Elsie and do it yourself, will take an hour to learn the software and 5 minutes to design the filter. Another good filter program that is free and available and relatively easy to use is at the AADE website. Would be worth your while to learn even if you seldom design a filter. W4ZCB "Peter O. Brackett" wrote in message hlink.net... Paul: [snip] I need a simple design for a BPF with a centre frequency of 17.2Mhz., corner frequencies one Meg or therabouts either side of that and a reasonably good shape factor (nothing critical here). I don't mind having to do a bit of tweaking of values myself if anyone has something close to that they can post. Passive L/C combinations only, please. (assume the usual 50R nominal Zs.) [snip] Such a design can be achieved with a vert simple formula and a pocket calculator or slide rule. Why don't you just use Bennett's simple formula for the maximally flat approximation all pole element values, or Takashi's simple formulae for the equiripple approximation all pole element values? Oh... perhaps you want elliptic [Cauer or Darlington] designs or perhaps a completely general parameter design in that case ypu will need a computer and will need to do some programming or buy some programming, or better yet... Hire a consultant... :-) Hey, I've designed literally thousands of LC filters over decades in most frequency ranges, for clients who have paid me well. I have access to very sophisticated and comprehensive general parameter LC filter design programs that I have written [In Fortran BTW] over lo these many years and they are immediately at my disposal. But... unfortunately for some... I never design filters for free! I'll do it for you at my usual consulting rates. My rates are reasonable. Just call or email me to discuss the terms and conditions. :-) -- Peter Professional Consultant - Signal Processing and Analog Electronics Indialantic By-the-Sea, FL peter dot brackett at "eye" triple "e" dot org. USA area code three two one, number seven two three, nine two five five. "Paul Burridge" wrote in message ... Hi all, I need a simple design for a BPF with a centre frequency of 17.2Mhz., corner frequencies one Meg or therabouts either side of that and a reasonably good shape factor (nothing critical here). I don't mind having to do a bit of tweaking of values myself if anyone has something close to that they can post. Passive L/C combinations only, please. (assume the usual 50R nominal Zs.) Thanks, p. -- The BBC: Licensed at public expense to spread lies. |
Conversely, go to the WB6BLD website and download the free student version
of Elsie and do it yourself, will take an hour to learn the software and 5 minutes to design the filter. Another good filter program that is free and available and relatively easy to use is at the AADE website. Would be worth your while to learn even if you seldom design a filter. W4ZCB "Peter O. Brackett" wrote in message hlink.net... Paul: [snip] I need a simple design for a BPF with a centre frequency of 17.2Mhz., corner frequencies one Meg or therabouts either side of that and a reasonably good shape factor (nothing critical here). I don't mind having to do a bit of tweaking of values myself if anyone has something close to that they can post. Passive L/C combinations only, please. (assume the usual 50R nominal Zs.) [snip] Such a design can be achieved with a vert simple formula and a pocket calculator or slide rule. Why don't you just use Bennett's simple formula for the maximally flat approximation all pole element values, or Takashi's simple formulae for the equiripple approximation all pole element values? Oh... perhaps you want elliptic [Cauer or Darlington] designs or perhaps a completely general parameter design in that case ypu will need a computer and will need to do some programming or buy some programming, or better yet... Hire a consultant... :-) Hey, I've designed literally thousands of LC filters over decades in most frequency ranges, for clients who have paid me well. I have access to very sophisticated and comprehensive general parameter LC filter design programs that I have written [In Fortran BTW] over lo these many years and they are immediately at my disposal. But... unfortunately for some... I never design filters for free! I'll do it for you at my usual consulting rates. My rates are reasonable. Just call or email me to discuss the terms and conditions. :-) -- Peter Professional Consultant - Signal Processing and Analog Electronics Indialantic By-the-Sea, FL peter dot brackett at "eye" triple "e" dot org. USA area code three two one, number seven two three, nine two five five. "Paul Burridge" wrote in message ... Hi all, I need a simple design for a BPF with a centre frequency of 17.2Mhz., corner frequencies one Meg or therabouts either side of that and a reasonably good shape factor (nothing critical here). I don't mind having to do a bit of tweaking of values myself if anyone has something close to that they can post. Passive L/C combinations only, please. (assume the usual 50R nominal Zs.) Thanks, p. -- The BBC: Licensed at public expense to spread lies. |
On Thu, 04 Mar 2004 23:43:21 +0000, Paul Burridge
wrote: Hi all, I need a simple design for a BPF with a centre frequency of 17.2Mhz., corner frequencies one Meg or therabouts either side of that and a reasonably good shape factor (nothing critical here). I don't mind having to do a bit of tweaking of values myself if anyone has something close to that they can post. Passive L/C combinations only, please. (assume the usual 50R nominal Zs.) Thanks, p. The usual technique is to get a book that has tables of normalized LC lowpass filters of various types, pick a response you like, and scale it and map to a bandpass. Williams' "Electronic Filter Design Handbook" has all this stuff. It's mildly tedious, so I won't offer to do one for you. John |
On Thu, 04 Mar 2004 23:43:21 +0000, Paul Burridge
wrote: Hi all, I need a simple design for a BPF with a centre frequency of 17.2Mhz., corner frequencies one Meg or therabouts either side of that and a reasonably good shape factor (nothing critical here). I don't mind having to do a bit of tweaking of values myself if anyone has something close to that they can post. Passive L/C combinations only, please. (assume the usual 50R nominal Zs.) Thanks, p. The usual technique is to get a book that has tables of normalized LC lowpass filters of various types, pick a response you like, and scale it and map to a bandpass. Williams' "Electronic Filter Design Handbook" has all this stuff. It's mildly tedious, so I won't offer to do one for you. John |
Paul Burridge wrote:
Hi all, I need a simple design for a BPF with a centre frequency of 17.2Mhz., corner frequencies one Meg or therabouts either side of that and a reasonably good shape factor (nothing critical here). I don't mind having to do a bit of tweaking of values myself if anyone has something close to that they can post. Passive L/C combinations only, please. (assume the usual 50R nominal Zs.) If you have Office 2002 (XP), you can use this web site. http://www.rfcafe.com/references/_sp...er_plot_ss.htm -- A man, a plan, a cat, a canal - Panama! Ho, ho, ho, hee, hee, hee and a couple of ha, ha, has; That's how we pass the day away, in the merry old land of Oz. |
Paul Burridge wrote:
Hi all, I need a simple design for a BPF with a centre frequency of 17.2Mhz., corner frequencies one Meg or therabouts either side of that and a reasonably good shape factor (nothing critical here). I don't mind having to do a bit of tweaking of values myself if anyone has something close to that they can post. Passive L/C combinations only, please. (assume the usual 50R nominal Zs.) If you have Office 2002 (XP), you can use this web site. http://www.rfcafe.com/references/_sp...er_plot_ss.htm -- A man, a plan, a cat, a canal - Panama! Ho, ho, ho, hee, hee, hee and a couple of ha, ha, has; That's how we pass the day away, in the merry old land of Oz. |
On Thu, 04 Mar 2004 23:43:21 +0000, Paul Burridge
wrote: Hi all, I need a simple design for a BPF with a centre frequency of 17.2Mhz., corner frequencies one Meg or therabouts either side of that and a reasonably good shape factor (nothing critical here). I don't mind having to do a bit of tweaking of values myself if anyone has something close to that they can post. Passive L/C combinations only, please. (assume the usual 50R nominal Zs.) Thanks, p. Try this 5 pole Chebychev with 0.1dB ripple Fc=17.2MHz BW=1MHz CAP 1 2 C=27PF PLC 2 0 L=1uH C=56PF CAP 2 3 C=4PF PLC 3 0 L=.1uH C=80PF CAP 3 4 C=3PF PLC 4 0 L=1uH C=80PF CAP 4 5 C=3PF PLC 5 0 L=1uH C=80PF CAP 5 6 C=4PF PLC 6 0 L=1uH C=56PF CAP 6 7 C=27PF tia, Remove "HeadFromButt", before replying by email. |
On Thu, 04 Mar 2004 23:43:21 +0000, Paul Burridge
wrote: Hi all, I need a simple design for a BPF with a centre frequency of 17.2Mhz., corner frequencies one Meg or therabouts either side of that and a reasonably good shape factor (nothing critical here). I don't mind having to do a bit of tweaking of values myself if anyone has something close to that they can post. Passive L/C combinations only, please. (assume the usual 50R nominal Zs.) Thanks, p. Try this 5 pole Chebychev with 0.1dB ripple Fc=17.2MHz BW=1MHz CAP 1 2 C=27PF PLC 2 0 L=1uH C=56PF CAP 2 3 C=4PF PLC 3 0 L=.1uH C=80PF CAP 3 4 C=3PF PLC 4 0 L=1uH C=80PF CAP 4 5 C=3PF PLC 5 0 L=1uH C=80PF CAP 5 6 C=4PF PLC 6 0 L=1uH C=56PF CAP 6 7 C=27PF tia, Remove "HeadFromButt", before replying by email. |
On Fri, 05 Mar 2004 03:08:22 GMT, maxfoo wrote:
On Thu, 04 Mar 2004 23:43:21 +0000, Paul Burridge wrote: Hi all, I need a simple design for a BPF with a centre frequency of 17.2Mhz., corner frequencies one Meg or therabouts either side of that and a reasonably good shape factor (nothing critical here). I don't mind having to do a bit of tweaking of values myself if anyone has something close to that they can post. Passive L/C combinations only, please. (assume the usual 50R nominal Zs.) Thanks, p. Try this 5 pole Chebychev with 0.1dB ripple Fc=17.2MHz BW=1MHz CAP 1 2 C=27PF PLC 2 0 L=1uH C=56PF CAP 2 3 C=4PF PLC 3 0 L=.1uH C=80PF L=1uH sorry! CAP 3 4 C=3PF PLC 4 0 L=1uH C=80PF CAP 4 5 C=3PF PLC 5 0 L=1uH C=80PF CAP 5 6 C=4PF PLC 6 0 L=1uH C=56PF CAP 6 7 C=27PF how did that decimal point get there on plc 3 0?? inductors should all be 1 microhenry. Remove "HeadFromButt", before replying by email. |
On Fri, 05 Mar 2004 03:08:22 GMT, maxfoo wrote:
On Thu, 04 Mar 2004 23:43:21 +0000, Paul Burridge wrote: Hi all, I need a simple design for a BPF with a centre frequency of 17.2Mhz., corner frequencies one Meg or therabouts either side of that and a reasonably good shape factor (nothing critical here). I don't mind having to do a bit of tweaking of values myself if anyone has something close to that they can post. Passive L/C combinations only, please. (assume the usual 50R nominal Zs.) Thanks, p. Try this 5 pole Chebychev with 0.1dB ripple Fc=17.2MHz BW=1MHz CAP 1 2 C=27PF PLC 2 0 L=1uH C=56PF CAP 2 3 C=4PF PLC 3 0 L=.1uH C=80PF L=1uH sorry! CAP 3 4 C=3PF PLC 4 0 L=1uH C=80PF CAP 4 5 C=3PF PLC 5 0 L=1uH C=80PF CAP 5 6 C=4PF PLC 6 0 L=1uH C=56PF CAP 6 7 C=27PF how did that decimal point get there on plc 3 0?? inductors should all be 1 microhenry. Remove "HeadFromButt", before replying by email. |
On Thu, 04 Mar 2004 23:43:21 +0000, Paul Burridge
wrote: Hi all, I need a simple design for a BPF with a centre frequency of 17.2Mhz., corner frequencies one Meg or therabouts either side of that and a reasonably good shape factor (nothing critical here). I don't mind having to do a bit of tweaking of values myself if anyone has something close to that they can post. Passive L/C combinations only, please. (assume the usual 50R nominal Zs.) Lots of books out there with normalized tables. Go to a technical university library and spend a few hours pouring thru some filter books. You can use Linear Technology's FilterCad to see what sort of filter type and order you need. Then hit the tables and make an LC filter. The best book I have found is "Simplified Modern Filter Design" by Philip Geffe, circa 1963. You can sometimes find this book in a university technical library. It has an excellent treatment of basic filter design and how to go from a low-pass prototype to other filter types. For your particular filter, you might consider a loose-coupled design, also called coupled resonators. Good for Q 10. Your design will just fit into this category if you don't mind some imperfection. This type of design produces nice component values. "Electronic Filter Design Handbook", by Arthur Williams and Fred Taylor (ISBN 0-07-070434-1), page 5-19 has info. Mark |
On Thu, 04 Mar 2004 23:43:21 +0000, Paul Burridge
wrote: Hi all, I need a simple design for a BPF with a centre frequency of 17.2Mhz., corner frequencies one Meg or therabouts either side of that and a reasonably good shape factor (nothing critical here). I don't mind having to do a bit of tweaking of values myself if anyone has something close to that they can post. Passive L/C combinations only, please. (assume the usual 50R nominal Zs.) Lots of books out there with normalized tables. Go to a technical university library and spend a few hours pouring thru some filter books. You can use Linear Technology's FilterCad to see what sort of filter type and order you need. Then hit the tables and make an LC filter. The best book I have found is "Simplified Modern Filter Design" by Philip Geffe, circa 1963. You can sometimes find this book in a university technical library. It has an excellent treatment of basic filter design and how to go from a low-pass prototype to other filter types. For your particular filter, you might consider a loose-coupled design, also called coupled resonators. Good for Q 10. Your design will just fit into this category if you don't mind some imperfection. This type of design produces nice component values. "Electronic Filter Design Handbook", by Arthur Williams and Fred Taylor (ISBN 0-07-070434-1), page 5-19 has info. Mark |
AADE http://www.aade.com/filter.htm
"Paul Burridge" wrote in message ... Hi all, I need a simple design for a BPF with a centre frequency of 17.2Mhz., corner frequencies one Meg or therabouts either side of that and a reasonably good shape factor (nothing critical here). I don't mind having to do a bit of tweaking of values myself if anyone has something close to that they can post. Passive L/C combinations only, please. (assume the usual 50R nominal Zs.) Thanks, p. -- The BBC: Licensed at public expense to spread lies. |
AADE http://www.aade.com/filter.htm
"Paul Burridge" wrote in message ... Hi all, I need a simple design for a BPF with a centre frequency of 17.2Mhz., corner frequencies one Meg or therabouts either side of that and a reasonably good shape factor (nothing critical here). I don't mind having to do a bit of tweaking of values myself if anyone has something close to that they can post. Passive L/C combinations only, please. (assume the usual 50R nominal Zs.) Thanks, p. -- The BBC: Licensed at public expense to spread lies. |
"Paul Burridge" wrote in message ... Hi all, I need a simple design for a BPF with a centre frequency of 17.2Mhz., corner frequencies one Meg or therabouts either side of that and a reasonably good shape factor (nothing critical here). I don't mind having to do a bit of tweaking of values myself if anyone has something close to that they can post. Passive L/C combinations only, please. (assume the usual 50R nominal Zs.) Thanks, p. -- The BBC: Licensed at public expense to spread lies. Download the freeware filter design software from http://www.nuhertz.com/ Their UI is, uh, colorful, but it seems to work. Pay attention to the source and load impedance. Also, it doesn't like 'engineering' notation (eg: 17.2Meg), so use scientific notation like 17.2e6 instead. The freeware only designs filters to 3rd order, so if you need better than that, either dig it out of a book or buy the software. However, it does both passive and active filters. Its a bargain at twice the price... ;) Regards, Bob Monsen |
"Paul Burridge" wrote in message ... Hi all, I need a simple design for a BPF with a centre frequency of 17.2Mhz., corner frequencies one Meg or therabouts either side of that and a reasonably good shape factor (nothing critical here). I don't mind having to do a bit of tweaking of values myself if anyone has something close to that they can post. Passive L/C combinations only, please. (assume the usual 50R nominal Zs.) Thanks, p. -- The BBC: Licensed at public expense to spread lies. Download the freeware filter design software from http://www.nuhertz.com/ Their UI is, uh, colorful, but it seems to work. Pay attention to the source and load impedance. Also, it doesn't like 'engineering' notation (eg: 17.2Meg), so use scientific notation like 17.2e6 instead. The freeware only designs filters to 3rd order, so if you need better than that, either dig it out of a book or buy the software. However, it does both passive and active filters. Its a bargain at twice the price... ;) Regards, Bob Monsen |
Download RFSim99 and let it do it for you. Download Filter Design
from AADE's site and let it do it for you. Download NuHertz's demo version of their filter design software and let it do it for you. There may even be web aplets that will do it for you. And then you can play with configurations and shape factors and the inevitable tradeoffs between complexity and shape factor. Cheers, Tom Paul Burridge wrote in message . .. Hi all, I need a simple design for a BPF with a centre frequency of 17.2Mhz., corner frequencies one Meg or therabouts either side of that and a reasonably good shape factor (nothing critical here). I don't mind having to do a bit of tweaking of values myself if anyone has something close to that they can post. Passive L/C combinations only, please. (assume the usual 50R nominal Zs.) Thanks, p. |
Download RFSim99 and let it do it for you. Download Filter Design
from AADE's site and let it do it for you. Download NuHertz's demo version of their filter design software and let it do it for you. There may even be web aplets that will do it for you. And then you can play with configurations and shape factors and the inevitable tradeoffs between complexity and shape factor. Cheers, Tom Paul Burridge wrote in message . .. Hi all, I need a simple design for a BPF with a centre frequency of 17.2Mhz., corner frequencies one Meg or therabouts either side of that and a reasonably good shape factor (nothing critical here). I don't mind having to do a bit of tweaking of values myself if anyone has something close to that they can post. Passive L/C combinations only, please. (assume the usual 50R nominal Zs.) Thanks, p. |
For a very simple bandpass design program download program BANDPAS1 from
website below. Also obtain response versus frequency. Download in a few seconds and run immediately. -- .................................................. .......... Regards from Reg, G4FGQ For Free Radio Design Software go to http://www.btinternet.com/~g4fgq.regp .................................................. .......... |
For a very simple bandpass design program download program BANDPAS1 from
website below. Also obtain response versus frequency. Download in a few seconds and run immediately. -- .................................................. .......... Regards from Reg, G4FGQ For Free Radio Design Software go to http://www.btinternet.com/~g4fgq.regp .................................................. .......... |
On Thu, 04 Mar 2004 17:58:26 -0800, John Larkin wrote:
On Thu, 04 Mar 2004 23:43:21 +0000, Paul Burridge wrote: Hi all, I need a simple design for a BPF with a centre frequency of 17.2Mhz., corner frequencies one Meg or therabouts either side of that and a reasonably good shape factor (nothing critical here). wtf? I don't mind having to do a bit of tweaking of values myself if anyone has something close to that they can post. Passive L/C combinations only, please. (assume the usual 50R nominal Zs.) Thanks, p. The usual technique is to get a book that has tables of normalized LC lowpass filters of various types, pick a response you like, and scale it and map to a bandpass. Williams' "Electronic Filter Design Handbook" has all this stuff. It's mildly tedious, so I won't offer to do one for you. John He already has a book with a fair amount of tables and all the explainations on how to go about the design. I'm wondering WTF here. Hey paul. wtf? -- Best Regards, Mike |
On Thu, 04 Mar 2004 17:58:26 -0800, John Larkin wrote:
On Thu, 04 Mar 2004 23:43:21 +0000, Paul Burridge wrote: Hi all, I need a simple design for a BPF with a centre frequency of 17.2Mhz., corner frequencies one Meg or therabouts either side of that and a reasonably good shape factor (nothing critical here). wtf? I don't mind having to do a bit of tweaking of values myself if anyone has something close to that they can post. Passive L/C combinations only, please. (assume the usual 50R nominal Zs.) Thanks, p. The usual technique is to get a book that has tables of normalized LC lowpass filters of various types, pick a response you like, and scale it and map to a bandpass. Williams' "Electronic Filter Design Handbook" has all this stuff. It's mildly tedious, so I won't offer to do one for you. John He already has a book with a fair amount of tables and all the explainations on how to go about the design. I'm wondering WTF here. Hey paul. wtf? -- Best Regards, Mike |
On Fri, 05 Mar 2004 11:28:51 GMT, Active8
wrote: He already has a book with a fair amount of tables and all the explainations on how to go about the design. I'm wondering WTF here. Hey paul. wtf? Fair point. I just wondered if anyone had a design similar to requirements *already* lying around they might post it, that's all. Save me a bit of scrawling and button-pushing. I didn't wish to put anyone out. Thanks to all who responded, BTW. Some very useful steers. -- The BBC: Licensed at public expense to spread lies. |
On Fri, 05 Mar 2004 11:28:51 GMT, Active8
wrote: He already has a book with a fair amount of tables and all the explainations on how to go about the design. I'm wondering WTF here. Hey paul. wtf? Fair point. I just wondered if anyone had a design similar to requirements *already* lying around they might post it, that's all. Save me a bit of scrawling and button-pushing. I didn't wish to put anyone out. Thanks to all who responded, BTW. Some very useful steers. -- The BBC: Licensed at public expense to spread lies. |
Hi Paul,
E-mail me directly and let me know how many poles you need. I have the AADE program, and I will be glad to do that for you. Pete "Paul Burridge" wrote in message ... On Fri, 05 Mar 2004 11:28:51 GMT, Active8 wrote: He already has a book with a fair amount of tables and all the explainations on how to go about the design. I'm wondering WTF here. Hey paul. wtf? Fair point. I just wondered if anyone had a design similar to requirements *already* lying around they might post it, that's all. Save me a bit of scrawling and button-pushing. I didn't wish to put anyone out. Thanks to all who responded, BTW. Some very useful steers. -- The BBC: Licensed at public expense to spread lies. |
Hi Paul,
E-mail me directly and let me know how many poles you need. I have the AADE program, and I will be glad to do that for you. Pete "Paul Burridge" wrote in message ... On Fri, 05 Mar 2004 11:28:51 GMT, Active8 wrote: He already has a book with a fair amount of tables and all the explainations on how to go about the design. I'm wondering WTF here. Hey paul. wtf? Fair point. I just wondered if anyone had a design similar to requirements *already* lying around they might post it, that's all. Save me a bit of scrawling and button-pushing. I didn't wish to put anyone out. Thanks to all who responded, BTW. Some very useful steers. -- The BBC: Licensed at public expense to spread lies. |
Paul Burridge wrote in message ... Hi all, I need a simple design for a BPF with a centre frequency of 17.2Mhz., corner frequencies one Meg or therabouts either side of that and a reasonably good shape factor (nothing critical here). I don't mind having to do a bit of tweaking of values myself if anyone has something close to that they can post. Passive L/C combinations only, please. (assume the usual 50R nominal Zs.) Thanks, p. -- The BBC: Licensed at public expense to spread lies. The simplest filter that'll get you by, is this one. (a couple of tuned circuits with a bit of top-coupling :-) ... ___ ||C1 -|_R_¦------.----.-------||-------.----.-------, O/p Source |L2 |C2 || |C2 |L2 | I/p | | | | .-. C| --- --- C| | |load R C| --- --- C| |R| C| | | C| '-' | | | | | === === === === === GND GND GND GND GND F1=16.2e6 'lower limit MHz F2=18.2e6 'upper limit MHz R=50 'Ohms source and load impedance Pi=3.142 C1 = (F1+F2) / (4 x Pi x F1 x F2 x R) C2 = F1 /(Pi x F2 x (F2-F1) x R)/2 L2 = 2xR /(4 x Pi) x (1/F1 - 1/F2) The inductors end up being quite small but a couple of loops of wire cost nothing. At 25megs the output is down to about 3% , which is not bad. This particular style is the "3 element" design and from the traditional "Constant K" filter stable. The pleasantly simple to design "constant K's" and associated "M derived" filters, can be easily and freely used for most day-to-day electronics work. Exact Filter design, or 'synthesis' as they nowadays prefer to call it, can be a nightmare if you're coming in from scratch. Even using a filter design programme requires a good knowledge of filter types/performance/spec's before data can begin to be entered. If not using a prog' you move onto the more vexing method of having to design an initial (prototype) low-pass filter, either via precalculated tables or computing the required co-efficients, then mathematically transforming the low-pass values into a bandpass (etc) design. For higher order filters it can be ball-acheing drudgery and even then inductor resistance has a nasty habit of spoiling that pristine work of art. (not a problem with DSP filters). I can't suggest a decent book, as the general purpose books seem over complicated and destined to be written by maths people for maths people. (The old GPO line-comm's manuals have useful notes on the 'K and M ' filters). regards john |
Paul Burridge wrote in message ... Hi all, I need a simple design for a BPF with a centre frequency of 17.2Mhz., corner frequencies one Meg or therabouts either side of that and a reasonably good shape factor (nothing critical here). I don't mind having to do a bit of tweaking of values myself if anyone has something close to that they can post. Passive L/C combinations only, please. (assume the usual 50R nominal Zs.) Thanks, p. -- The BBC: Licensed at public expense to spread lies. The simplest filter that'll get you by, is this one. (a couple of tuned circuits with a bit of top-coupling :-) ... ___ ||C1 -|_R_¦------.----.-------||-------.----.-------, O/p Source |L2 |C2 || |C2 |L2 | I/p | | | | .-. C| --- --- C| | |load R C| --- --- C| |R| C| | | C| '-' | | | | | === === === === === GND GND GND GND GND F1=16.2e6 'lower limit MHz F2=18.2e6 'upper limit MHz R=50 'Ohms source and load impedance Pi=3.142 C1 = (F1+F2) / (4 x Pi x F1 x F2 x R) C2 = F1 /(Pi x F2 x (F2-F1) x R)/2 L2 = 2xR /(4 x Pi) x (1/F1 - 1/F2) The inductors end up being quite small but a couple of loops of wire cost nothing. At 25megs the output is down to about 3% , which is not bad. This particular style is the "3 element" design and from the traditional "Constant K" filter stable. The pleasantly simple to design "constant K's" and associated "M derived" filters, can be easily and freely used for most day-to-day electronics work. Exact Filter design, or 'synthesis' as they nowadays prefer to call it, can be a nightmare if you're coming in from scratch. Even using a filter design programme requires a good knowledge of filter types/performance/spec's before data can begin to be entered. If not using a prog' you move onto the more vexing method of having to design an initial (prototype) low-pass filter, either via precalculated tables or computing the required co-efficients, then mathematically transforming the low-pass values into a bandpass (etc) design. For higher order filters it can be ball-acheing drudgery and even then inductor resistance has a nasty habit of spoiling that pristine work of art. (not a problem with DSP filters). I can't suggest a decent book, as the general purpose books seem over complicated and destined to be written by maths people for maths people. (The old GPO line-comm's manuals have useful notes on the 'K and M ' filters). regards john |
Go to Alt Binaries Schematics -
bg Paul Burridge wrote in message ... Hi all, I need a simple design for a BPF with a centre frequency of 17.2Mhz., |
Go to Alt Binaries Schematics -
bg Paul Burridge wrote in message ... Hi all, I need a simple design for a BPF with a centre frequency of 17.2Mhz., |
John Jardine wrote:
I can't suggest a decent book, as the general purpose books seem over complicated and destined to be written by maths people for maths people. I'd suggest Temes and LaPatra, "Circuit Synthesis and Design." Now out of print, but occasionally you can find a cheap old copy used. I'd also suggest the original poster does a couple of the exercises (he might have already), doing what you describe with building a low frequency prototype filter and then transforming it to a different type and frequency range, but just for, e.g., a second order filter. There's not much to be gained by doing the 'drudgery,' as you say, for a higher order filter other than proficiency in aithrmetic. ---Joel Kolstad |
John Jardine wrote:
I can't suggest a decent book, as the general purpose books seem over complicated and destined to be written by maths people for maths people. I'd suggest Temes and LaPatra, "Circuit Synthesis and Design." Now out of print, but occasionally you can find a cheap old copy used. I'd also suggest the original poster does a couple of the exercises (he might have already), doing what you describe with building a low frequency prototype filter and then transforming it to a different type and frequency range, but just for, e.g., a second order filter. There's not much to be gained by doing the 'drudgery,' as you say, for a higher order filter other than proficiency in aithrmetic. ---Joel Kolstad |
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On Fri, 05 Mar 2004 16:18:32 +0000, Paul Burridge wrote:
On Fri, 05 Mar 2004 11:28:51 GMT, Active8 wrote: He already has a book with a fair amount of tables and all the explainations on how to go about the design. I'm wondering WTF here. Hey paul. wtf? Fair point. I just wondered if anyone had a design similar to requirements *already* lying around they might post it, that's all. Save me a bit of scrawling and button-pushing. I didn't wish to put anyone out. Thanks to all who responded, BTW. Some very useful steers. Yes. I had to check my disorganized drive to make sure I'd been to all those links. BTDT. I like having tools like that around to compare what they say with what I figgered out on paper. -- Best Regards, Mike |
On Fri, 05 Mar 2004 16:18:32 +0000, Paul Burridge wrote:
On Fri, 05 Mar 2004 11:28:51 GMT, Active8 wrote: He already has a book with a fair amount of tables and all the explainations on how to go about the design. I'm wondering WTF here. Hey paul. wtf? Fair point. I just wondered if anyone had a design similar to requirements *already* lying around they might post it, that's all. Save me a bit of scrawling and button-pushing. I didn't wish to put anyone out. Thanks to all who responded, BTW. Some very useful steers. Yes. I had to check my disorganized drive to make sure I'd been to all those links. BTDT. I like having tools like that around to compare what they say with what I figgered out on paper. -- Best Regards, Mike |
On Thu, 04 Mar 2004 23:43:21 +0000, Paul Burridge
wrote: Hi all, I need a simple design for a BPF with a centre frequency of 17.2Mhz., corner frequencies one Meg or therabouts either side of that and a reasonably good shape factor (nothing critical here). I don't mind having to do a bit of tweaking of values myself if anyone has something close to that they can post. Passive L/C combinations only, please. (assume the usual 50R nominal Zs.) Thanks, Since your too lazy to do this, here, have a few designs. You can run these on LTSpice. What is reasonably good shape factor? Mark Butterworth, pi-input, 1st-order low-pass prototype Vin 1 0 AC 2.0000V Rin 1 2 50.000 L1 2 0 26.899n C1 2 0 3.1831n Rout 2 0 50.000 ..AC DEC 396 253.58kHz 1.1667GHz ..PROBE ..END Butterworth, pi-input, 2nd-order low-pass prototype Vin 1 0 AC 2.0000V Rin 1 2 50.000 L1 2 0 38.041n C1 2 0 2.2508n L2 2 3 5.6270u C2 3 4 15.216p Rout 4 0 50.000 ..AC DEC 792 5.7378MegHz 51.560MegHz ..PROBE ..END Butterworth, loose coupled, 2nd-order low-pass prototype Vin 1 0 AC 2.0000V Rin 1 2 50.000 C1 2 0 2.0654nF L1 2 0 38.046nH C2 2 3 185.01pF C3 3 0 2.0654nF L2 3 0 38.046nH Rout 3 0 50.000 ..AC DEC 792 5.7378MegHz 51.560MegHz ..PROBE ..END Butterworth, pi-input, 3rd-order low-pass prototype Vin 1 0 AC 2.0000V Rin 1 2 50.000 L1 2 0 53.798n C1 2 0 1.5915n L2 2 3 7.9577u C2 3 4 10.760p L3 4 0 53.798n C3 4 0 1.5915n Rout 4 0 50.000 ..AC DEC 1188 10.224MegHz 28.937MegHz ..PROBE ..END Butterworth, loose coupled, 3rd-order low-pass prototype Vin 1 0 AC 2.0000V Rin 1 2 50.000 C1 2 0 1.4607nF L1 2 0 53.798nH C2 2 3 130.84pF C3 3 0 1.3299nF L2 3 0 53.798nH C4 3 4 130.84pF C5 4 0 1.4607nF L3 4 0 53.798nH Rout 4 0 50.000 ..AC DEC 1188 10.224MegHz 28.937MegHz ..PROBE ..END Butterworth, loose coupled, 8th-order low-pass prototype Vin 1 0 AC 2.0000V Rin 1 2 50.000 C1 2 0 511.07pF L1 2 0 137.94nH C2 2 3 109.63pF C3 3 0 457.95pF L2 3 0 137.94nH C4 3 4 53.121pF C5 4 0 527.60pF L3 4 0 137.94nH C6 4 5 39.985pF C7 5 0 543.91pF L4 5 0 137.94nH C8 5 6 36.809pF C9 6 0 543.91pF L5 6 0 137.94nH C10 6 7 39.985pF C11 7 0 527.60pF L6 7 0 137.94nH C12 7 8 53.121pF C13 8 0 457.95pF L7 8 0 137.94nH C14 8 9 109.63pF C15 9 0 511.07pF L8 9 0 137.94nH Rout 9 0 50.000 ..AC DEC 3170 15.208MegHz 19.453MegHz ..PROBE ..END |
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