Rethinking filters
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I've got my K3S on order and was planning to transfer some of my filters
from my K3 before selling it but after reviewing the filter specs along with my past experience I'm rethinking the narrow end. I've got a 13Khz filter which I'll transfer but I'm thinking of selling the 250 8p pair in favor of a 400hz 4p pair. Also thinking of getting rid of my singleton 200hz 4p and getting a matched pair of 200hz 4p. I find that the 250hz 8p (actually 350hz) are a bit narrow for RTTY so I often open the filter window to 400+ hz. I've been using the 200hz 4p primarily for ekeing out the last bit of signal on 160m and I'm planning to go diversity this next season. So I'd like to combine diversity with the 200hz bandwidth. Comments welcome. 73 jim ab3cv ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
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On Fri,5/15/2015 3:39 PM, Jim Miller wrote:
> I've got my K3S on order and was planning to transfer some of my filters > from my K3 before selling it but after reviewing the filter specs along > with my past experience I'm rethinking the narrow end. In his annual Dayton talk yesterday, Rob Sherwood said that he had seen some serious IM issues with some Elecraft roofing filters. I would hold off on buying any new filters for a while until I knew a lot more about that issue. 73, Jim K9YC ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
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> In his annual Dayton talk yesterday, Rob Sherwood said that he had > seen some serious IM issues with some Elecraft roofing filters. I've been e-mailing with Rob - some of my spare filters have been among his test subjects. The issue is passive IMD in the filter itself ... in essence when the interfering signal levels get high enough, the filters start to behave as non-linear devices and seem to develop a short term "memory." This applies to both the 5 pole and 8 pole filters. Of note is that the signal levels necessary to generate this passive IMD is nearly 10dB higher than the former reciprocal mixing (phase noise) limited dynamic range values with the "old" synthesizer. It is much like pealing an onion ... once one limitation is removed another item in the signal chain becomes the weak link. It may be necessary to test filters to a higher standard. I understand some test systems are already under development. 73, ... Joe, W4TV On 2015-05-15 8:02 PM, Jim Brown wrote: > On Fri,5/15/2015 3:39 PM, Jim Miller wrote: >> I've got my K3S on order and was planning to transfer some of my filters >> from my K3 before selling it but after reviewing the filter specs along >> with my past experience I'm rethinking the narrow end. > > In his annual Dayton talk yesterday, Rob Sherwood said that he had seen > some serious IM issues with some Elecraft roofing filters. I would hold > off on buying any new filters for a while until I knew a lot more about > that issue. > > 73, Jim K9YC > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[hidden email] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to [hidden email] > Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
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In reply to this post by Jim AB3CV
I use matched 200 Hz filters in diversity (Beverages + RX4SQ) and APF nearly 100% of the time on 160...even when doing S&P in contests. I can get away with this because CW Skimmer allows me to exactly zero beat when jumping from one station to another in Blind Mode (i.e. as a bandscope without decoding). Although I also have dual Inrad 500 Hz filters, I find I seldom use them. 73, Bill W4ZV |
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In reply to this post by Joe Subich, W4TV-4
On Fri,5/15/2015 6:14 PM, Joe Subich, W4TV wrote:
> Of note is that the signal levels necessary to generate this passive > IMD is nearly 10dB higher than the former reciprocal mixing (phase > noise) limited dynamic range values with the "old" synthesizer. It is > much like pealing an onion ... once one limitation is removed another > item in the signal chain becomes the weak link. Exactly! Quite common in the field of engineering, especially EMC -- slaying some of the larger dragons exposes smaller ones nipping at our heels. 73, Jim K9YC ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
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In reply to this post by Jim Brown-10
This IM issue was 1st reported in the Jan 2009 QST review on K3
Sidebar "A Close Look at K3 Roofing Filters" The 200hz filter was not included in write up & the issue seemed to be the 1800hz filter which if I recall - Elecraft said was issue with the supplier & it was resolved... Hope Rob will post his data here or his web pages! K4TV - thanks for input on use of the dual 200hz, nice on the subject of K3 & K3S Great rigs for sure except operator interface still lacking, no attempt to get dedicated band stacking buttons OK 73 Robert W5AJ -----Original Message----- From: Elecraft [mailto:[hidden email]] On Behalf Of Jim Brown Sent: Friday, May 15, 2015 7:02 PM To: [hidden email] Subject: Re: [Elecraft] Rethinking filters On Fri,5/15/2015 3:39 PM, Jim Miller wrote: > I've got my K3S on order and was planning to transfer some of my > filters from my K3 before selling it but after reviewing the filter > specs along with my past experience I'm rethinking the narrow end. In his annual Dayton talk yesterday, Rob Sherwood said that he had seen some serious IM issues with some Elecraft roofing filters. I would hold off on buying any new filters for a while until I knew a lot more about that issue. 73, Jim K9YC ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
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On Fri,5/15/2015 8:27 PM, Robert Wood wrote:
> This IM issue was 1st reported in the Jan 2009 QST review on K3 > Sidebar "A Close Look at K3 Roofing Filters" Thanks., Robert. That's something I either missed or forgot. :) > The 200hz filter was not included in write up & the issue seemed to be the > 1800hz filter which if I recall - Elecraft said was issue with the supplier > & it was resolved... That would be Inrad for the 8-pole filters. They're a good company, so I'd bet it will be this time around too. Bob, Wayne, and Eric are all in Dayton, so there's a good chance they will huddle. > on the subject of K3 & K3S > Great rigs for sure except operator interface still lacking, no attempt to > get dedicated band stacking buttons I'm happy with the user interface. What are "dedicated band stacking buttons? 73, Jim K9YC ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
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In reply to this post by Jim Brown-10
Old subject.
http://martein.home.xs4all.nl/pa3ake/hmode/IF_filters.html There is some fantastic info in these papers. Wes N7WS On 5/15/2015 5:02 PM, Jim Brown wrote: > On Fri,5/15/2015 3:39 PM, Jim Miller wrote: >> I've got my K3S on order and was planning to transfer some of my filters >> from my K3 before selling it but after reviewing the filter specs along >> with my past experience I'm rethinking the narrow end. > > In his annual Dayton talk yesterday, Rob Sherwood said that he had seen some > serious IM issues with some Elecraft roofing filters. I would hold off on > buying any new filters for a while until I knew a lot more about that issue. > > 73, Jim K9YC > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
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Further to this, for those who believe that down-conversion is a must for good
RX performance here is some food for thought. http://martein.home.xs4all.nl/pa3ake/hmode/g3sbi_intro.html On 5/16/2015 7:49 AM, Wes (N7WS) wrote: > Old subject. > > http://martein.home.xs4all.nl/pa3ake/hmode/IF_filters.html > > There is some fantastic info in these papers. > > Wes N7WS > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [hidden email] |
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