Re: [Elecraft] Filter Question
Hi Wilson, The response of the DSP IF filters combines (cascades) with the roofing filters; when both are the same bandwidth, their skirts fall off much more sharply (the rolloff is equal to the sum of the two filters). When one is much broader than the other, we get only the skirts of the narrowest one. This is generally true of all filters, whether digital or analog, except to the extent that the combined phase shift modifies the total response. 73, Jim K9YC On 9/9/2020 10:24 AM, Wilson Lamb wrote: Would someone please explain the relationship between our plug in filters (K3) and the variable filter response provided by our width control. As I understand the situation, the plug in filters we buy are roofing filters, used to prevent intermod from strong signals outside the pass band. Is there more to it? __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] Filter Question
You understand it well. The plug in filters work before the AtoD converter and protect it from desense due to strong nearby signals. Desense occurs when the ALC reduces receive sensitivity because of this strong signal. This level of suppression can be useful with other hams operating nearby, like a neighbor or a multi-radio operation like field day with both CW and digital stations. The width control works with the DSP filter to provide finer control of the bandwidth. By narrowing the passband, you can reduce the total band noise coming through the receiver and improve the signal to noise ratio for the desired signal. You can also use it to suppress a strong, slightly off frequency, signal. Without other signals, the width control will work the same with or without the plug in filters. The ifs/ands/and buts are that if both filters are set to about the same width, the skirts will be a bit sharper. (DSP filters tend to have very sharp skirts.) 73 Bill AE6JV On 9/9/20 at 1:24 PM, info...@embarqmail.com (Wilson Lamb) wrote: Would someone please explain the relationship between our plug in filters (K3) and the variable filter response provided by our width control. As I understand the situation, the plug in filters we buy are roofing filters, used to prevent intermod from strong signals outside the pass band. Is there more to it? If there were no other signals, would the width control work the same with and without the plug in filters? --- Bill Frantz| Truth and love must prevail | Periwinkle (408)348-7900 | over lies and hate. | 150 Rivermead Rd #235 www.pwpconsult.com | - Vaclav Havel | Peterborough, NH 03458 __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
Re: [Elecraft] Filter question
Jim: just one more comment: I have the 1.8, but it's a little too touchy for fast tuning in contests for me. I went ahead and got the 2.1 for that reason. Hope this helps. 73, Fred AE6IC __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] Filter question
On Mon, 18 Feb 2008 15:18:45 -0800 (PST), you wrote: Ultimately, the 15 khz FM filter would be the best choice for roofing AM and FM (on receive). I have ordered the FM filter for use in AM BC reception. But now I am reconsidering since someone has said that AM BC sounds so good with one sideband through the 6 khz filter. I wonder if the performance benefits of the narrower filter will outweigh the better fidelity of the wide filter. Oh, well, still have a couple of months to decide... 73, Drew AF2Z ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
Re: [Elecraft] Filter question
There'll be times that we'll want to listen to AM on only one sideband or the other to get rid of interference on the other side, but no matter how good it may sound that way, I still want the synchronous detector and DSP wide enough to benefit from the 12 KHz filter when conditions allow. I enjoyed that on my 746Pro too much to be happy with narrow AM broadcast. I'd sure hate to go back to an Icom just to have better AM receive. So I'm waiting to see what the good guys can do. Dave W5DHM I have ordered the FM filter for use in AM BC reception. But now I am reconsidering since someone has said that AM BC sounds so good with one sideband through the 6 khz filter. I wonder if the performance benefits of the narrower filter will outweigh the better fidelity of the wide filter. Oh, well, still have a couple of months to decide... 73, Drew AF2Z ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
Re: [Elecraft] Filter question
From the K3 FAQs (see http://www.elecraft.com/K3/K3FAQ.htm) Q: I'm still not clear on the general-coverage (GC) receive option -- if it is indeed optional or available by default in a minimally configured radio. The basic radio, as well as the subreceiver, has a full array of ham-band-only filters at the front end. This is to ensure excellent performance in the ham bands. These filters are switched in by means of relays. The KBPF3 option is a small plug-in module that sits above the ham-band filters. It, too, has a number of filters switched in by relays. The difference is that these are wider filters, covering all of the area between the ham bands. But they share the same input/output path as the ham-band filters. When not selected, the GC filters have absolutely no effect on performance, thanks to a very careful layout that minimizes trace lengths. When you tune the radio well outside the ham bands, an appropriate GC filter is automatically selected by firmware. Hopes this helps -- at least with your KBPF3 question. Mark AD5SS ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
Re: [Elecraft] Filter question
Hi Bill, You need the KBPF3 filter if the BBC is not broadcasting in or near a Ham radio band. The BBC generally does not do this. You also need the KBPF3 if you want to listen to medium wave. You need the 6kHz filter to listen to AM with good fidelity. Conclusion: Imho, you will want to have both. vy 73 de toby Bill Kimura wrote: Thank you Toby! Just so I'm clear, the 6kHz filter would allow me to listen to the UK BBC, etc. at full fidelity, and the KBPF3 module wouldn't be needed? It may be helpful if you could provide me with an example of when I would NEED the KBPF3 module. Thanks again for the quick reply. - Bill ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
Re: [Elecraft] Filter question
Hi Bill, The standard front end filters are tuned to the Ham bands only. Far enough outside of our bands the receiver will loose a lot of sensitivity because of this. To cover the regions used e.g. by broadcasters you need the KBPF3. This has nothing to do with the roofing filters. Depending upon your need to transmit AM and or listen to AM in a higher quality, you can use either the SSB filter for reception only (you listen to either the upper or lower sideband using SSB), or you need the 6kHz filter for real AM demodulation, which also gives you the ability to transmit AM. I wouldn't use the FM filter for this, but ymmv. For FM you will need the FM filter. Also if you want to add the second rx, don't forget that it needs its own filters. It does not share the KBPF3 or roofing filters with the main rx. Hope this helps, vy 73 de toby ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
RE: [Elecraft] Filter question
Does the KBPF3 go into the RX module or the main board module? Ie do you need two if you have the dual receivers? You probably wouldn't need dual RX out of band but just a wonder I guess the band passes would have to be on the RX modules or you wouldn't be able to get the two RX modules onto frequencies on two separate bands True? -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Mark Bayern Sent: Monday, February 18, 2008 1:55 PM To: Bill Kimura Cc: elecraft@mailman.qth.net Subject: Re: [Elecraft] Filter question From the K3 FAQs (see http://www.elecraft.com/K3/K3FAQ.htm) Q: I'm still not clear on the general-coverage (GC) receive option -- if it is indeed optional or available by default in a minimally configured radio. The basic radio, as well as the subreceiver, has a full array of ham-band-only filters at the front end. This is to ensure excellent performance in the ham bands. These filters are switched in by means of relays. The KBPF3 option is a small plug-in module that sits above the ham-band filters. It, too, has a number of filters switched in by relays. The difference is that these are wider filters, covering all of the area between the ham bands. But they share the same input/output path as the ham-band filters. When not selected, the GC filters have absolutely no effect on performance, thanks to a very careful layout that minimizes trace lengths. When you tune the radio well outside the ham bands, an appropriate GC filter is automatically selected by firmware. Hopes this helps -- at least with your KBPF3 question. Mark AD5SS ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
