KX3 PBT problem
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I have RX xFIL set to "normal" in the menu so that the PBT control adjusts
bandwidth. When I use a BW of 1.8 KHz or higher in SSB mode, everything looks good on a waterfall display. But when I reduce the BW to 1.7 KHz or lower, a chunk approximately 250 Hz wide and centered at 1500 Hz is removed from the waterfall display. I originally thought it was related to the roofing filters as the effect happened at the same time that FL2 was selected, but after I set the roofing filters to "not installed" so that FL1 was used for all bandwidths, the problems still occurs. Any suggestions would be appreciated. KX3-K serial #1691 with latest production release firmware installed. The roofing filter option was ordered with the transceiver. 73, AL - VE3RRD ______________________________________________________________ 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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Hi Al,
Haven't tried it or observed it but I think that what you see is the switch to weaver mode demodulating. I thought this would only occurred when the filter was installed but from your observation I'd say that's not so. I think what you're seeing is normal. There's an IF shift (or something similar) which moves the centre of the demodulated space up to 8KHz. This will also prevent the KX3 from switching to weaver mode and supress the hole in the centre of the demodulated audio but will confirm there's nothing un-natural going on. Weaver mode is essential to provide the minimal roofing filter width in direct conversion SDR architecture. In SSB mode the hole is of no consequence and not audible. In digital modes it can be supressed by keeping the IF bandwidth high. The 8KHz IF mode is really there to supress low frequency punch through from things like local AM broadcast station interference. 73's Peter VK4JD -----Original Message----- From: Elecraft [mailto:[hidden email]] On Behalf Of Al Duncan Sent: Friday, 4 September 2015 12:56 AM To: [hidden email] Subject: [Elecraft] KX3 PBT problem I have RX xFIL set to "normal" in the menu so that the PBT control adjusts bandwidth. When I use a BW of 1.8 KHz or higher in SSB mode, everything looks good on a waterfall display. But when I reduce the BW to 1.7 KHz or lower, a chunk approximately 250 Hz wide and centered at 1500 Hz is removed from the waterfall display. I originally thought it was related to the roofing filters as the effect happened at the same time that FL2 was selected, but after I set the roofing filters to "not installed" so that FL1 was used for all bandwidths, the problems still occurs. Any suggestions would be appreciated. KX3-K serial #1691 with latest production release firmware installed. The roofing filter option was ordered with the transceiver. 73, AL - VE3RRD ______________________________________________________________ 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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Hi Peter,
It is odd that the Weaver mode is used when I "uninstall" the roofing filters and the display shows it is only using FL1. I just tried enabling the 8 KHz RX shift, both with and without the roofing filter installed, but the problem still shows up. I am exiting from the menu and power-cycling the KX3 after I make any menu changes to ensure they are in effect. 73, AL - VE3RRD -----Original Message----- From: Peter Lambert [mailto:[hidden email]] Sent: Thursday, September 03, 2015 4:14 PM To: 'Al Duncan'; [hidden email] Subject: RE: [Elecraft] KX3 PBT problem Hi Al, Haven't tried it or observed it but I think that what you see is the switch to weaver mode demodulating. I thought this would only occurred when the filter was installed but from your observation I'd say that's not so. I think what you're seeing is normal. There's an IF shift (or something similar) which moves the centre of the demodulated space up to 8KHz. This will also prevent the KX3 from switching to weaver mode and supress the hole in the centre of the demodulated audio but will confirm there's nothing un-natural going on. Weaver mode is essential to provide the minimal roofing filter width in direct conversion SDR architecture. In SSB mode the hole is of no consequence and not audible. In digital modes it can be supressed by keeping the IF bandwidth high. The 8KHz IF mode is really there to supress low frequency punch through from things like local AM broadcast station interference. 73's Peter VK4JD -----Original Message----- From: Elecraft [mailto:[hidden email]] On Behalf Of Al Duncan Sent: Friday, 4 September 2015 12:56 AM To: [hidden email] Subject: [Elecraft] KX3 PBT problem I have RX xFIL set to "normal" in the menu so that the PBT control adjusts bandwidth. When I use a BW of 1.8 KHz or higher in SSB mode, everything looks good on a waterfall display. But when I reduce the BW to 1.7 KHz or lower, a chunk approximately 250 Hz wide and centered at 1500 Hz is removed from the waterfall display. I originally thought it was related to the roofing filters as the effect happened at the same time that FL2 was selected, but after I set the roofing filters to "not installed" so that FL1 was used for all bandwidths, the problems still occurs. Any suggestions would be appreciated. KX3-K serial #1691 with latest production release firmware installed. The roofing filter option was ordered with the transceiver. 73, AL - VE3RRD ______________________________________________________________ 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 Peter Lambert
Yet another reason you should use DATA-A mode for digital modes rather than SSB.
73, Matt VK2RQ Envoyé à partir d'Outlook _____________________________ From: Peter Lambert <[hidden email]> Sent: vendredi, septembre 4, 2015 6:15 AM Subject: Re: [Elecraft] KX3 PBT problem To: Al Duncan <[hidden email]>, <[hidden email]> Hi Al, Haven't tried it or observed it but I think that what you see is the switch to weaver mode demodulating. I thought this would only occurred when the filter was installed but from your observation I'd say that's not so. ______________________________________________________________ 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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Hi Matt,
Thanks for the suggestion, I was playing around with FSQ digital mode on 14104, 10144 and 7104 USB but couldnt set my bandwidth narrow enough. In DATA-A I can now make it as narrow as I want. 73, AL VE3RRD _____ From: Matt Maguire [mailto:[hidden email]] Sent: Thursday, September 03, 2015 4:55 PM To: Al Duncan; Peter Lambert; [hidden email] Subject: Re: [Elecraft] KX3 PBT problem Yet another reason you should use DATA-A mode for digital modes rather than SSB. 73, Matt <x-apple-data-detectors://0> VK2RQ Envoyé à partir d'Outlook <http://aka.ms/Ox5hz3> ______________________________________________________________ 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 ve3rrd
Al,
That sounds like the switch to Weaver demodulation below 1.8 kHz is causing the 'hole' in your waterfall - that is used for SSB voice reception. Use DATA A (or AFSK A for RTTY) instead of SSB to avoid that condition. 73, Don W3FPR On 9/3/2015 10:55 AM, Al Duncan wrote: > I have RX xFIL set to "normal" in the menu so that the PBT control adjusts > bandwidth. When I use a BW of 1.8 KHz or higher in SSB mode, everything > looks good on a waterfall display. But when I reduce the BW to 1.7 KHz or > lower, a chunk approximately 250 Hz wide and centered at 1500 Hz is removed > from the waterfall display. I originally thought it was related to the > roofing filters as the effect happened at the same time that FL2 was > selected, but after I set the roofing filters to "not installed" so that FL1 > was used for all bandwidths, the problems still occurs. Any suggestions > would be appreciated. > > KX3-K serial #1691 with latest production release firmware installed. The > roofing filter option was ordered with the transceiver. > > 73, AL - VE3RRD > > > > > > ______________________________________________________________ > 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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