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Electronics Repair (sci.electronics.repair) Discussion of repairing electronic equipment. Topics include requests for assistance, where to obtain servicing information and parts, techniques for diagnosis and repair, and annecdotes about success, failures and problems. |
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Butterworth bandpass filter question
I am trying to scale an existing front end receiver (butterworth
bandpass) filter to a different frequency range. Unfortunately, it has a transformer in the original design, so I'm stuck. I also don't know how to handle the load presented by the active front end component other than it's probably not significantly reactive. The existing filter is for a 7 Mhz receiver, I'd like to have a similar filter design for 50 to 200 Khz. The filter components and transformer winding details are in the document at: http://www.amqrp.org/kits/softrock40...0Assy%20v1.pdf The input chip is an FST3126, spec sheet is at: http://www.fairchildsemi.com/ds/FS/FST3126.pdf The spec for the T30-2 transformer core is at: http://partsandkits.com/T30-2.htm I have aade filter design software, but it isn't allowing me to plug in the transformer into the design page of the software....so, I need to know it's equivalent circuit I think. The transformer winding details are on page 4 of the document and the schematic of the front end is page 9. Ultimately, I need new values for L1, L2, C20, C21 and C22. If someone can give me a reasonable guess as to the equivalent circuit of the transformer and the IC (U5), I can do the rest of the job myself using the aade filter software. Thanks, T |
#2
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On Sun, 11 Sep 2005 12:14:11 -0400, TRABEM wrote:
Get the free software program call RFsim99 lets you design buttrworth filters. |
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I am trying to scale an existing front end receiver (butterworth
bandpass) filter to a different frequency range. ===================================== How do you know it is a Butterworth as distinct from other types? |
#4
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A butterworth is a butterworth............in any discussion of the
butterworth filter, you will see this schematic. Asking how I know it's a butterworth is a little like asking how I know a car is a car. However, I don't know it all.........perhaps it's closely related to a butterworth, but called something else??? Let me know if I've made an error please. T On Mon, 12 Sep 2005 06:07:31 +0000 (UTC), "Reg Edwards" wrote: I am trying to scale an existing front end receiver (butterworth bandpass) filter to a different frequency range. ===================================== How do you know it is a Butterworth as distinct from other types? |
#5
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TRABEM schrieb im Newsbeitrag
news A butterworth is a butterworth............in any discussion of the butterworth filter, you will see this schematic. Asking how I know it's a butterworth is a little like asking how I know a car is a car. However, I don't know it all.........perhaps it's closely related to a butterworth, but called something else??? Let me know if I've made an error please. T Hello T, a Bessel filter would have the same structure. The value of the components define what filter type it is. Bessel: max. flat group delay Butterworth: max flat frequency response You can also make a filter with this structure which is anything between both types. Best regards, Helmut |
#6
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a Bessel filter would have the same structure. The value of the components define what filter type it is. Bessel: max. flat group delay Butterworth: max flat frequency response Cool, didn't know that. At VLF, the inductances are becoming quite large, requiring a toroid core for even a simple inductor. What are the advantages/disadvantages of each type relative to inductor size requirements? Maybe I should be looking at a bessel instead of a butterworth....... GL to all. T |
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On Mon, 12 Sep 2005 12:18:52 -0400, TRABEM wrote:
A butterworth is a butterworth............in any discussion of the butterworth filter, you will see this schematic. Asking how I know it's a butterworth is a little like asking how I know a car is a car. However, I don't know it all.........perhaps it's closely related to a butterworth, but called something else??? Let me know if I've made an error please. T On Mon, 12 Sep 2005 06:07:31 +0000 (UTC), "Reg Edwards" wrote: I am trying to scale an existing front end receiver (butterworth bandpass) filter to a different frequency range. ===================================== How do you know it is a Butterworth as distinct from other types? A Butterworth filter is a Chebyshev filter with No ripple in the passband. |
#8
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"TRABEM" bravely wrote to "All" (12 Sep 05 12:18:52)
--- on the heady topic of " Butterworth bandpass filter question" I thought it was a turkey until I opened a filter cookbook... Isn't it flat smooth response without overshoot as opposed to Tchebychev with a little overshoot but faster risetime? Bessel is something in between these? Where do they find these names!!! M*i*k*e TR From: TRABEM TR Subject: Butterworth bandpass filter question TR Xref: core-easynews sci.electronics.components:101732 TR sci.electronics.design:505281 sci.electronics.repair:341949 TR A butterworth is a butterworth............in any discussion of the TR butterworth filter, you will see this schematic. TR Asking how I know it's a butterworth is a little like asking how I TR know a car is a car. TR However, I don't know it all.........perhaps it's closely related to a TR butterworth, but called something else??? TR Let me know if I've made an error please. TR T TR On Mon, 12 Sep 2005 06:07:31 +0000 (UTC), "Reg Edwards" TR wrote: I am trying to scale an existing front end receiver (butterworth bandpass) filter to a different frequency range. =3d=3d=3d=3d=3d=3d=3d=3d=3d=3d=3d=3d=3d=3d=3d=3d= 3d=3d=3d=3d=3d=3d=3d=3d=3d=3d=3d=3d=3d=3d=3d=3d=3d =3d=3d=3d=3d How do you know it is a Butterworth as distinct from other types? .... If all else fails, hurl it across the room a few times! |
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