Title: Dallas Lankford Amplified Elliptic Low Pass Audio Filters simplified & approved Post by: k7iou on May 03, 2014, 08:30:32 AM Does anyone have the complete article ? I found one online but it stops mid sentence on page 5.
Amplified Elliptic Low Pass Audio Filters simplified and approved Dallas Lankford 5/29/06 rev. 5/26/08 http://docs4.chomikuj.pl/1992242688,PL,0,0,ELPAFs.pdf 73 de k7iou Title: Re: Dallas Lankford Amplified Elliptic Low Pass Audio Filters simplified & approved Post by: Opcom on May 03, 2014, 09:25:39 AM there is a yahoo group here that might have it.
http://www.kongsfjord.no/dl.htm Title: Re: Dallas Lankford Amplified Elliptic Low Pass Audio Filters simplified & approved Post by: k7iou on May 03, 2014, 09:49:54 AM Thanks, I sent an email out to the group. I checked out the group before but was disappointed that nothing is posted there, files etc.
de k7iou Title: Re: Dallas Lankford Amplified Elliptic Low Pass Audio Filters simplified & approved Post by: pa0ast on May 03, 2014, 12:33:55 PM Elsie is a programm to calculate LC filters . The student version is free... See http://tonnesoftware.com/elsie.html
Interesting nice programm , works OK. The input and output impedance is very important. I use differential mains coils of 2x 50mH and put the coils in serie to get a 200mH coil for less then a dollar. Adjusting is possible to add windings by drilling a hole in the center and ad the wire though it. Perfect for designing lowpass audio filters. I measured some designs and if properly loaded the figures are as calculated. see photo. a steep 3.5 kHz loww pass filter at 7kC 60 dB down 4kOhm in and output imp. With small coil values the in and output imp is quite high. With big coils You can go low f.i. 200 Ohm or so. Anton Title: Re: Dallas Lankford Amplified Elliptic Low Pass Audio Filters simplified & approved Post by: k7iou on May 03, 2014, 08:14:38 PM there is a yahoo group here that might have it. I joined but no messages are allowed except by a moderator. There are no files posted. I don't understand why the group exists????? Seems worthless as a group to me.http://www.kongsfjord.no/dl.htm My messages were returned, to <thedallasfiles2@yahoogroups.com>. Your message was not delivered because it was sent to an announcement-only group, where only the moderator may post. A copy of your original message is attached. Title: Re: Dallas Lankford Amplified Elliptic Low Pass Audio Filters simplified & approved Post by: Opcom on May 03, 2014, 08:31:00 PM That's kind of silly. Maybe it is a cobweb, squatter, or placeholder.
I was very happy with Elsie as well as with Linear's program. Title: Re: Dallas Lankford Amplified Elliptic Low Pass Audio Filters simplified & approved Post by: k7iou on May 03, 2014, 09:00:38 PM Getting off topic
Please keep it to the original post and question. Title: Re: Dallas Lankford Amplified Elliptic Low Pass Audio Filters simplified & approved Post by: KA0HCP on May 03, 2014, 09:13:01 PM It seems appropriate to discuss where to find Dallas Lankford information, since that IS the original topic.
From what I've been able to gather Mr. Lankford pulled his work from the internet a few years ago and moved it to a limited access Yahoo discussion group. I had tried to access that group a couple years ago without success. Apparently during the Yahoo discussion group reorganization a year or so ago, the files were lost, leaving Lankford to rebuild... I'm not sure what drove him to remove his works from public access. It's quite unfortunate considering how prolific he was, and that he originally was inspired to share his knowledge. b. Title: Re: Dallas Lankford Amplified Elliptic Low Pass Audio Filters simplified & approved Post by: k7iou on May 03, 2014, 09:24:12 PM It seems appropriate to discuss where to find Dallas Lankford information, since that IS the original topic. I wondered what happened to his work. Now I know and I agree with you about his work.Elsie software is not the topic I posted. From what I've been able to gather Mr. Lankford pulled his work from the internet a few years ago and moved it to a limited access Yahoo discussion group. I had tried to access that group a couple years ago without success. Apparently during the Yahoo discussion group reorganization a year or so ago, the files were lost, leaving Lankford to rebuild... I'm not sure what drove him to remove his works from public access. It's quite unfortunate considering how prolific he was, and that he originally was inspired to share his knowledge. b. Title: Re: Dallas Lankford Amplified Elliptic Low Pass Audio Filters simplified & approved Post by: k7iou on May 03, 2014, 09:30:30 PM Squatter
That's kind of silly. Maybe it is a cobweb, squatter, or placeholder. I was very happy with Elsie as well as with Linear's program. Title: Re: Dallas Lankford Amplified Elliptic Low Pass Audio Filters simplified & approved Post by: KA0HCP on May 03, 2014, 10:41:52 PM I am finding the "Wayback Machine" to be invaluable in recovering lost internet data.
Here is the Dallas Files from the kongsfjord.no (sp) website from Nov 2010. This is the last archive date before the files were deleted in 2011/2012. https://web.archive.org/web/20101124124237/http://kongsfjord.no/dl/dl.htm I believe this is the last revision of the elliptical filters article updated 5/26/08 https://web.archive.org/web/20101124132846/http://kongsfjord.no/dl/Audio/ELPAFs.pdf You can browse earlier capture dates using the forward/back arrows on the Wayback display. bill Title: Re: Dallas Lankford Amplified Elliptic Low Pass Audio Filters simplified & approved Post by: w3jn on May 03, 2014, 11:32:38 PM Getting off topic Please keep it to the original post and question. It most certainly is on topic and a good contribution to the thread. Please resist the temptation to backseat moderate. Title: Re: Dallas Lankford Amplified Elliptic Low Pass Audio Filters simplified & approved Post by: k7iou on May 04, 2014, 09:53:41 AM I am finding the "Wayback Machine" to be invaluable in recovering lost internet data. Thank you Bill! This is it :)Here is the Dallas Files from the kongsfjord.no (sp) website from Nov 2010. This is the last archive date before the files were deleted in 2011/2012. https://web.archive.org/web/20101124124237/http://kongsfjord.no/dl/dl.htm I believe this is the last revision of the elliptical filters article updated 5/26/08 https://web.archive.org/web/20101124132846/http://kongsfjord.no/dl/Audio/ELPAFs.pdf You can browse earlier capture dates using the forward/back arrows on the Wayback display. bill https://web.archive.org/web/20101124132846/http://kongsfjord.no/dl/Audio/ELPAFs.pdf I was missing 2 pages. I believe Lankford's articles are a great contribution to the amateur radio community and I wish he would publish a book as I would be one of the first in line to buy one. 73 de k7iou Title: Re: Dallas Lankford Amplified Elliptic Low Pass Audio Filters simplified & approved Post by: nq5t on May 04, 2014, 10:26:43 AM I'd forgotten about web.archive. Went looking, and even found the ancient ham radio site (globeking.com) I took down many years ago. It was fun to see some of those old pics :) AMfone - Dedicated to Amplitude Modulation on the Amateur Radio Bands
Grant NQ5T |