Re: [Elecraft] Broadcast band interference [KX3}]
I posted a question concerning an issue with broadcast band interference on my KX3 and received several good replys. Here's more info on this issue.there is a local AM broadcast station about 8 miles away but that is not the one I'm hearing. It's sounding like a Shortwave AM broadcast from some religious station. Using the RX SHFT as suggested by one person replying is not a viable option. When you do that it disables the Roofing Filter option which I need usually for copying CW signals where I'm having the problem. I do have the antenna tuner installed and tuned to the band where I'm working but I'm still getting the problem. The signal does vary up and down in strength so I'm sure it's a Shortwave signal causing the problem. I can live with the problem most of the time but I would hope Elecraft could provide an answer to this issue. How about it Eric or Wayne? Any comments from your end? My KX3 is SN. 564 built by me in June of 2012. Gary A. - W0MNA __ 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] Broadcast band interference [KX3}]
Somewhere in the back of my head is a recollection of issues surrounding spurious signals caused by the mixing of strong signals in things like corroded gutter joints etc. If there is a strong signal present from the AM station at all times then the other signal varying in strength might cause his fade in and out issue. Can some who is a real engineer tell me if this makes sense or have I been smoking green leafy stuff? David K0LUM On Jan 9, 2013, at 9:15 AM, Gary Auchard wrote: I posted a question concerning an issue with broadcast band interference on my KX3 and received several good replys. Here's more info on this issue.there is a local AM broadcast station about 8 miles away but that is not the one I'm hearing. It's sounding like a Shortwave AM broadcast from some religious station. Using the RX SHFT as suggested by one person replying is not a viable option. When you do that it disables the Roofing Filter option which I need usually for copying CW signals where I'm having the problem. I do have the antenna tuner installed and tuned to the band where I'm working but I'm still getting the problem. The signal does vary up and down in strength so I'm sure it's a Shortwave signal causing the problem. I can live with the problem most of the time but I would hope Elecraft could provide an answer to this issue. How about it Eric or Wayne? Any comments from your end? My KX3 is SN. 564 built by me in June of 2012. Gary A. - W0MNA __ 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 __ 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] Broadcast band interference [KX3}]
Gary, Direct detection of AM signals is inherent problem with zero IF SDR. The best solution is the use of RX SHIFT. You can possibly use high Q filter at the input of the radio if you know the frequency of the interfering AM station and if it is only one such a station. But it is hardly practical solution. When RX shift is enabled you do lose narrow roofing but 15 kHz roofing is still in place. Without roofing filter the radio still has more then 90 db of IMD dynamic range which is more then enough in 99.9% of cases. Think of those using Yaesu and Icom rigs with DR of less then 80db and still winning contests. More valuable feature which is lost with RX shift engaged is DUAL RX. Yet Wayne promised, we will get DUAL RX with RX SHIFT in future firmware releases. 73, Igor UA9CDC - Original Message - From: Gary Auchard w0mn...@gmail.com To: Elecraft@mailman.qth.net Sent: Wednesday, January 09, 2013 9:15 PM Subject: Re: [Elecraft] Broadcast band interference [KX3}] I posted a question concerning an issue with broadcast band interference on my KX3 and received several good replys. Here's more info on this issue.there is a local AM broadcast station about 8 miles away but that is not the one I'm hearing. It's sounding like a Shortwave AM broadcast from some religious station. Using the RX SHFT as suggested by one person replying is not a viable option. When you do that it disables the Roofing Filter option which I need usually for copying CW signals where I'm having the problem. I do have the antenna tuner installed and tuned to the band where I'm working but I'm still getting the problem. The signal does vary up and down in strength so I'm sure it's a Shortwave signal causing the problem. I can live with the problem most of the time but I would hope Elecraft could provide an answer to this issue. How about it Eric or Wayne? Any comments from your end? My KX3 is SN. 564 built by me in June of 2012. Gary A. - W0MNA __ 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 __ 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] Broadcast band interference [KX3}]
While the rusty bolt syndrome is real, what is being discussed here is likely what is called am broadcast bleed through. This is a consequence of a direct conversion receiver and as I understand it is second order issue in the receivers front end, which basically makes it act as a detector to AM signals.It can be eliminated by using the 8 kHz offset in the kx3, or by filtering out the broadcast station before it gets to the antenna. If what you hear is resulting from an external mix (like from a rusty bolt) you will be able to tune away from it, since it will be on a discrete frequency, (although it might be wide, since it could have a harmonic aspect). If it is am bleed through it will be 'every where' since it is in effect getting into the radios IF which is not tunable (well it is if you use the 8 kHz offset). I'm sure not an RF or receiver designer but did find a lot of references about this on the web. The first ham SDRs had real issues with this. The kx3 seems to be much, much better. Mark. N2QT On Jan 9, 2013, at 11:38 AM, David Christ radio...@mchsi.com wrote: Somewhere in the back of my head is a recollection of issues surrounding spurious signals caused by the mixing of strong signals in things like corroded gutter joints etc. If there is a strong signal present from the AM station at all times then the other signal varying in strength might cause his fade in and out issue. Can some who is a real engineer tell me if this makes sense or have I been smoking green leafy stuff? David K0LUM On Jan 9, 2013, at 9:15 AM, Gary Auchard wrote: I posted a question concerning an issue with broadcast band interference on my KX3 and received several good replys. Here's more info on this issue.there is a local AM broadcast station about 8 miles away but that is not the one I'm hearing. It's sounding like a Shortwave AM broadcast from some religious station. Using the RX SHFT as suggested by one person replying is not a viable option. When you do that it disables the Roofing Filter option which I need usually for copying CW signals where I'm having the problem. I do have the antenna tuner installed and tuned to the band where I'm working but I'm still getting the problem. The signal does vary up and down in strength so I'm sure it's a Shortwave signal causing the problem. I can live with the problem most of the time but I would hope Elecraft could provide an answer to this issue. How about it Eric or Wayne? Any comments from your end? My KX3 is SN. 564 built by me in June of 2012. Gary A. - W0MNA __ 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 __ 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 __ 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] Broadcast band interference [KX3}]
Gary, As an alternative to using RX SHFT, you could try reducing gain in the RF section if you have the preamp on. Try preamp at the 10dB setting or preamp off. 73, Rich AC7MA On 01/09/2013 07:15 AM, Gary Auchard wrote: I posted a question concerning an issue with broadcast band interference on my KX3 and received several good replys. Here's more info on this issue.there is a local AM broadcast station about 8 miles away but that is not the one I'm hearing. It's sounding like a Shortwave AM broadcast from some religious station. Using the RX SHFT as suggested by one person replying is not a viable option. When you do that it disables the Roofing Filter option which I need usually for copying CW signals where I'm having the problem. I do have the antenna tuner installed and tuned to the band where I'm working but I'm still getting the problem. The signal does vary up and down in strength so I'm sure it's a Shortwave signal causing the problem. I can live with the problem most of the time but I would hope Elecraft could provide an answer to this issue. How about it Eric or Wayne? Any comments from your end? My KX3 is SN. 564 built by me in June of 2012. Gary A. - W0MNA __ 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
