Re: [Elecraft] K3 Overload from WYFR
Hi Lyle, You might try adding an attenuator between the K3 IF out and the LP-PAN IF in and see if the overloading disappears. If so, it might indicate the LP-PAN system is overloading rather than the K3. 73, Lyle KK7P PS - The K3 blocking dynamic range is 20 to 30 dB better than PC-based SDRs. So I suspect you are seeing a weakness in the PC-based SDR system rather than the K3, but I've been wrong before! :-) I'll probably have to eat Humble Pie, but with respect I don't believe that Steve has an overload problem, but could have a spurious mixing problem, the result being similar to intermodulation. Also, the problem might or might not be caused by the K3 nor LP-PAN, which would not be difficult to determine if another receiver is available. The screen capture of WYFR's carrier at 6985 kHz, and a family of products, shows that the spacing product to adjacent product is roughly 4.64 kHz if the low level intermediate products are ignored, which they can be in this exercise. If these products are the result of mixing (or are IMD products), there has to be of course another signal spaced 4.64 kHz from WYFR's carrier - and there is one at 6980.36 kHz, whose amplitude fits the amplitude pattern of the products. Of course, the device or transmitter generating this signal at 6980.36 kHz might in fact be operating at a sub-harmonic frequency e.g. a MF BC station, and the rogue mixer itself is generating the 6980.36 kHz harmonic. 73, Geoff GM4ESD __ 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] K3 Overload from WYFR
And the rogue mixer could be our old friends Rusty Bolt, Anode and Cathode. David G3UNA Of course, the device or transmitter generating this signal at 6980.36 kHz might in fact be operating at a sub-harmonic frequency e.g. a MF BC station, *and the rogue mixer itself is generating the 6980.36 kHz harmonic.* 73, Geoff GM4ESD __ 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] K3 Overload from WYFR
Yes indeed as both you and Joe, W4TV, have suggested before. Nickel plated coax connectors can create similar problems. Geoff GM4ESD David G3UNA wrote on Tuesday, June 16, 2009 at 3:19 PM And the rogue mixer could be our old friends Rusty Bolt, Anode and Cathode. David G3UNA Of course, the device or transmitter generating this signal at 6980.36 kHz might in fact be operating at a sub-harmonic frequency e.g. a MF BC station, *and the rogue mixer itself is generating the 6980.36 kHz harmonic.* 73, Geoff GM4ESD __ 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] K3 Overload from WYFR
Hi All, I was just wondering about the 40 m and started to listen to the AM broadcasts. I also found the nasty noises, but when I checked on the LP-Pan, I found the signal was ok. Of course, when I turned off the noise blanker it went away. Yet another senior moment. 73 Tim gm4lmh __ 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] K3 Overload from WYFR
Tim Heasman wrote: Of course, when I turned off the noise blanker it went away. In many cases you can use the DSP noise blanker instead of the IF blanker. The DSP blanker has the advantage of the narrow crystal filter ahead of it, and in many cases this will eliminate wideband intermod. Or try the two combined, with a less-aggressive setting of the IF blanker. 73, Wayne N6KR --- http://www.elecraft.com __ 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] K3 Overload from WYFR
Further to Joe's suggestion: I've heard of a strong local signal being rectified in rusty guttering giving problems to a beam in just one direction. Took years to find that one. Reminds me of something which happened many years ago here in Southern Germany. The interference monitoring and abatement service (at the time they were part of the German Post Office) received several complaints about TVI. The nearest ham was about 2km distant and when they checked his transmitter, the signal was clean. When they measured at the TV receiver there was a large harmonic on the same frequency as one of the TV stations. It turned out that one of the ham's neighbours had a narrow band, high gain television reception Yagi pointing towards the 2km distant TV. It turned out that there was some oxidation at the feed point of the Yagi, which acted as a diode. As you can imagine, this is the very short version of this true story. vy 73 de toby, DD5FZ __ 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] K3 Overload from WYFR
Hi Steve. Apparently there has been a problem with the messages to me from the LP-PAN Yahoo Group, so this digest is the first I am aware of your post. Sorry about that. I think it has been resolved now. It sounds like you may have to check your gain setting in LP-PAN, as well as the input level on your sound card. LP-PAN should easily be able to handle S9 + 60dB when set properly. What is the noise floor you are seeing on other bands? Do you have the K3 buffer mod installed? If so, you may need to remove it, or add a pad between the K3 and LP-PAN. Where do you have the gain pot in LP-PAN set? It should be set for minimum in your case. If you turn the input level of the sound card way down, do you still see the clipping? If so, you need to reduce the gain setting in LP-PAN. The first step in solving this is determine where the clipping is happening (K3, LP-PAN or sound card). 73, Larry N8LP Steve Ellington wrote: A photo (40 meter Overload) has been uploaded to the file section of the LP-PAN Yahoo Group. This photo is a screen capture from PowerSDR-IF showing WYFR at 6985Khz and the resulting images on either side of the carrier. The K3's preamp was off. Turning on ATTN reduces the levels somewhat but the images are still present. These images can be seen on PowerSDR all the way up to about 7080kHz while WYFR is transmitting however, tuning the K3's VFO to 7030kHz or above eliminates all signs of these images. Buckshot (distorted bits of modulation) can be heard up to about 7015Khz. The images shown seem to be generated by the LP-PAN. Clicking on them moves them elsewhere and they cannot be heard. Other than the buckshot at the low end of 40 meters, audible reception seems to be unaffected however LP-PAN is rendered unusable during the evenings. WYFR is located in Okeechobee, Florida, 631 miles from my QTH in NC. Naturally their signal is very strong, 60db+ over S9. The antenna used here is a 200ft doublet, ladder line and tuner. Here are my questions and concerns: 1. Is it normal to expect the K3's front end to overload under these conditions? 2. Is it normal for LP-Pan to be rendered useless by strong BC stations outside the ham bands like this? 3. Do you think this could be caused by any defect in the K3 or station configuration? 4. What kind, if any, outboard filter would help? The internal or external tuner has no effect (in or out of circuit). 5. Is anyone else experiencing such an overload? I'm just trying to pin down exactly where the problem is. It appears that the front end in the K3 is allowing too strong of a signal to hit the LP-PAN then the K3's roofing filters do their job to protect the K3's DSP. I have become rather addicted to the LP-PAN. I can't tell how many times I have though the band was dead after carefully tuning but a quick glance at the screen reveals several stations! If you are not subscribed to the LP-PAN group, you may view the photo here: http://i222.photobucket.com/albums/dd260/n4lq/wyfr.jpg 73 Steve N4LQ n...@carolina.rr.com __ 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 -- View this message in context: http://n2.nabble.com/K3-Overload-from-WYFR-tp3077727p3081584.html Sent from the Elecraft mailing list archive at Nabble.com. __ 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] K3 Overload from WYFR
1. Is it normal to expect the K3's front end to overload under these conditions? Are you sure the K3 front end is overloading and not the LP-PAN system (QSD, attached soundcard)? Are you experiencing symptoms that suggest reh K3 front end is overloading other than the LP-PAN display (which may be displaying the LP-PAN system, and in particular the soundcard ADC, overloading)? You might try adding an attenuator between the K3 IF out and the LP-PAN IF in and see if the overloading disappears. If so, it might indicate the LP-PAN system is overloading rather than the K3. 73, Lyle KK7P PS - The K3 blocking dynamic range is 20 to 30 dB better than PC-based SDRs. So I suspect you are seeing a weakness in the PC-based SDR system rather than the K3, but I've been wrong before! :-) __ 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] K3 Overload from WYFR
I would be checking your system (including the antenna and nearby structures) for problems ... I'm a whole lot closer to WYFR (105 miles) and they do not generate any overload or buckshot on my K3 with SDR-IQ and SpectraVue. 73, ... Joe, W4TV -Original Message- From: elecraft-boun...@mailman.qth.net [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Steve Ellington Sent: Sunday, June 14, 2009 8:32 PM To: Elecraft@mailman.qth.net; lp-...@yahoogroups.com Subject: [Elecraft] K3 Overload from WYFR A photo (40 meter Overload) has been uploaded to the file section of the LP-PAN Yahoo Group. This photo is a screen capture from PowerSDR-IF showing WYFR at 6985Khz and the resulting images on either side of the carrier. The K3's preamp was off. Turning on ATTN reduces the levels somewhat but the images are still present. These images can be seen on PowerSDR all the way up to about 7080kHz while WYFR is transmitting however, tuning the K3's VFO to 7030kHz or above eliminates all signs of these images. Buckshot (distorted bits of modulation) can be heard up to about 7015Khz. The images shown seem to be generated by the LP-PAN. Clicking on them moves them elsewhere and they cannot be heard. Other than the buckshot at the low end of 40 meters, audible reception seems to be unaffected however LP-PAN is rendered unusable during the evenings. WYFR is located in Okeechobee, Florida, 631 miles from my QTH in NC. Naturally their signal is very strong, 60db+ over S9. The antenna used here is a 200ft doublet, ladder line and tuner. Here are my questions and concerns: 1. Is it normal to expect the K3's front end to overload under these conditions? 2. Is it normal for LP-Pan to be rendered useless by strong BC stations outside the ham bands like this? 3. Do you think this could be caused by any defect in the K3 or station configuration? 4. What kind, if any, outboard filter would help? The internal or external tuner has no effect (in or out of circuit). 5. Is anyone else experiencing such an overload? I'm just trying to pin down exactly where the problem is. It appears that the front end in the K3 is allowing too strong of a signal to hit the LP-PAN then the K3's roofing filters do their job to protect the K3's DSP. I have become rather addicted to the LP-PAN. I can't tell how many times I have though the band was dead after carefully tuning but a quick glance at the screen reveals several stations! If you are not subscribed to the LP-PAN group, you may view the photo here: http://i222.photobucket.com/albums/dd260/n4lq/wyfr.jpg 73 Steve N4LQ n...@carolina.rr.com __ 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] K3 Overload from WYFR
You are using a doublet and tuner: to what frequency is the tuner tuned? Do you get the same response if the tuner is set differently? Further to Joe's suggestion: I've heard of a strong local signal being rectified in rusty guttering giving problems to a beam in just one direction. Took years to find that one. David G3UNA I would be checking your system (including the antenna and nearby structures) for problems ... I'm a whole lot closer to WYFR (105 miles) and they do not generate any overload or buckshot on my K3 with SDR-IQ and SpectraVue. 73, ... Joe, W4TV __ 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
