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Hi Carel An other interesting article about Ladder filter is the following: Designing and Building High Performance Crystal Ladder Filter by J.Makhinson in QEX Jan 1995 pp: 3- 17. The author uses the tools of Hayward (in Introduction to Radio Frequency Design) to develop high performance filters (low ripple, high shape factor.) I have used the Hayward and Makhinson papers to succesfully design several ladder filters some years ago: - 12 poles SSB filter (BW: 2.3kHz, IL: 2.5dB, S.F: 1.6) - 6 poles CW filters (BW 360Hz, I.L: 10dB) - 4 poles Noise filter (BW: 2.7kHz, I.L: 2.5dB) All these filters are 50 ohms and the input of the SSB one is connected to the post mixer amplifier via a 6dB attenuator in order to limit impedance changes. Good luck and 73's Roland Cordesses / F2DC 'Carel Mulder (PA0CMU)' a crit.
Designing and Building High Performance Crystal Ladder Filter by -J.Makhinson in QEX Jan 1995 pp: 3- 17. I'm having some trouble locating the two Hayward papers (QST May '82 and July '87) and don't have a CLUE where to find QEX. Does anybody know if these documents are available online anywhere? I can have my school library do a literature search and probably come up with copies, but they generally take half a semester to get the data.
![Crystal Filter Design Software Crystal Filter Design Software](/uploads/1/2/5/5/125529192/170012805.png)
Jim Jim Weir, VP Eng. WX6RST A&P, CFI, and other good alphabet soup. The Hayward article is included in an ARRL book 'QRP CLASSICS' and I believe it can still be ordered from ARRL. I also see it is in the ARRL book 'W1FB's DESIGN NOTEBOOK' and this is probably the better book to get, since it includes several other articles on crystal filter designs, and methods of measuring the crystals. As for QEX, there is a CDROM which ARRL has wiht issues from 1981 to 1998. I've built a ladder filter for 5.0000 MHz - CW bandwdth, and it was amazingly simple. Good luck, Jim Pennell N6BIU.
Software for designing crystal ladder filters: 1) “Dishal” by DJ6EV This software takes into account crystal parallel capacitance (Cp). Crystal Cp is a reason for crystal ladder bandwidth narrower than designed in theory.