K3 Roofing filters
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Dear Elecrafters,
I've been using my K2 for a dozen years and I'm thinking I might go for a K3. I have a question about RX filtering I'd like to get straight. Is the widest bandwidth available to the receiver the width of the widest roofing filter? I was wondering about getting the general coverage receive filter board, but I wanted to know if I'd be as well to get the AM (6kHz) roofing filter as well - or could I dial out beyond the stock 2.7 kHz? My usual mode is CW, so I know I'd want a narrow filter to help with - although I realise that the DSP does the filtering, the xtal filters provide roofing. 73, Paul EI5KI ______________________________________________________________ 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 |
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Correct. If you operate mostly CW, you may be wasting money getting wider filters than the stock 2.7 kHz...you definitely need a 500 Hz or lower filter for CW to prevent blocking in the presence of strong (S9+20) signals. 73, Bill W4ZV |
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In reply to this post by Paul Barlow-2
Paul,
The roofing filters protect the A to D converter input from strong adjacent signals, so choose your CW filter according to your operating habits. If you do CW contesting or DXing in pileup situations, you will want a narrow filter. If you are using the K3 as an SWL receiver, you would want either the 13 kHz or the 6 kHz roofing filter installed. The DSP audio bandpass will go out to about 4 kHz, so if you want full fidelity, choose the 13 kHz filter for that - AM bandwidth is double the audio bandwidth. The DSP width is displayed as the audio passband, the roofing filter is at the IF, so for AM double the audio bandwidth. 73, Don W3FPR On 10/10/2013 6:06 AM, Paul Barlow wrote: > Dear Elecrafters, > > I've been using my K2 for a dozen years and I'm thinking I might go for a > K3. I have a question about RX filtering I'd like to get straight. Is the > widest bandwidth available to the receiver the width of the widest roofing > filter? I was wondering about getting the general coverage receive filter > board, but I wanted to know if I'd be as well to get the AM (6kHz) roofing > filter as well - or could I dial out beyond the stock 2.7 kHz? > > My usual mode is CW, so I know I'd want a narrow filter to help with - > although I realise that the DSP does the filtering, the xtal filters provide > roofing. > ______________________________________________________________ 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 |
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In reply to this post by Paul Barlow-2
I think Paul had gotten the information he was asking about from
others Bill and Don. I don't see much use for the 6K filter since you can now use the 13K FM filter for AM transmit. If you do a lot of AM transmit you will have a cleaner signal with the 6K filter. If you only do AM receive, you can use the 2.7K or 2.8K filter to receive on only one sideband and get usable performance when conditions need narrower roofing than provided by the 13K filter. Save your filter slots for hard SSB, CW and digital conditions where roofing can be a lifesaver. Cheers - Bill, AE6JV ----------------------------------------------------------------------- Bill Frantz | I don't have high-speed | Periwinkle (408)356-8506 | internet. I have DSL. | 16345 Englewood Ave www.pwpconsult.com | | Los Gatos, CA 95032 ______________________________________________________________ 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 |
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> If you do a lot of AM transmit you will have a cleaner signal with > the 6K filter. Only marginally and only so far as it applies to synthesizer phase noise more than +/- 3 KHz from the carrier. Even then, the K3 will be much cleaner that the typical YaeComWood up-conversion transceiver with their 30 KHz wide 4 pole VHF filters. 73, ... Joe, W4TV On 10/10/2013 1:27 PM, Bill Frantz wrote: > I think Paul had gotten the information he was asking about from others > Bill and Don. > > I don't see much use for the 6K filter since you can now use the 13K FM > filter for AM transmit. If you do a lot of AM transmit you will have a > cleaner signal with the 6K filter. If you only do AM receive, you can > use the 2.7K or 2.8K filter to receive on only one sideband and get > usable performance when conditions need narrower roofing than provided > by the 13K filter. Save your filter slots for hard SSB, CW and digital > conditions where roofing can be a lifesaver. > > Cheers - Bill, AE6JV > > ----------------------------------------------------------------------- > Bill Frantz | I don't have high-speed | Periwinkle > (408)356-8506 | internet. I have DSL. | 16345 Englewood Ave > www.pwpconsult.com | | Los Gatos, CA 95032 > > ______________________________________________________________ > 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 > 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 |
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