P3 SVGA interference -
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In response to my message May 23, 2012; 3:27pm on the Elecraft P3
reflector Roger White W5RDW in Murphy, Texas responded off-list. He had the same problem I described. It was not coming from the K3 but from inside the P3. We both noted it started after installing the SVGA. During our investigation we boy found: 1 - the signal is about 5kHz wide 2 - it moves either up or down in frequency ever so slowly 3 - moving the VFO does not change the position of the signal - internal to P3? 4 - reach back and approach the IF signal coax between the K3 & P3 causes it to temporarily go away 5 - sometimes touching the P3 cabinet caused it to disappear 6 - changed out the coax but it still happens When the signal crosses the VFO frequency no sound is heard - only the signal being listened to. But reaching back in the proximity of the linking coax causes it to go away. Turning PC and other gear off has no effect. Roger and I spent sometime isolating the source. We found a signal was coupling into the IF cable inside the P3 from the ribbon cable. As you can see from the SVGA instruction manual the ribbon cable is so long that if not dressed it goes across the P3 and pushes up against the IF coax in the unit. When the ribbon cable is dressed by folding it tightly keeping it well away from the IF coax the wondering signal no longer appears. If you are having this anomaly Roger and I recommend making the change to the ribbon cable as shown in the two pictures below. It would be nice to have a shorter ribbon cable. 73, Bob - W6OPO Roger - W5RDW ______________________________________________________________ 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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Is it possible the ribbon cable is as long as it is because it will need to
eventually be routed around something else to be added later? Art - N4PJ On Tue, May 29, 2012 at 2:10 AM, Bob Lanning <[hidden email]>wrote: > In response to my message May 23, 2012; 3:27pm on the Elecraft P3 > reflector Roger White W5RDW in Murphy, Texas responded off-list. He had > the same problem I described. It was not coming from the K3 but from > inside the P3. We both noted it started after installing the SVGA. > > During our investigation we boy found: > > 1 - the signal is about 5kHz wide > 2 - it moves either up or down in frequency ever so slowly > 3 - moving the VFO does not change the position of the signal - internal > to P3? > 4 - reach back and approach the IF signal coax between the K3 & P3 > causes it to temporarily go away > 5 - sometimes touching the P3 cabinet caused it to disappear > 6 - changed out the coax but it still happens > > When the signal crosses the VFO frequency no sound is heard - only the > signal being listened to. But reaching back in the proximity of the > linking coax causes it to go away. Turning PC and other gear off has no > effect. > > Roger and I spent sometime isolating the source. We found a signal was > coupling into the IF cable inside the P3 from the ribbon cable. As you > can see from the SVGA instruction manual the ribbon cable is so long > that if not dressed it goes across the P3 and pushes up against the IF > coax in the unit. > > When the ribbon cable is dressed by folding it tightly keeping it well > away from the IF coax the wondering signal no longer appears. > > If you are having this anomaly Roger and I recommend making the change > to the ribbon cable as shown in the two pictures below. It would be > nice to have a shorter ribbon cable. > > 73, > > Bob - W6OPO > Roger - W5RDW > > ______________________________________________________________ > 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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In reply to this post by Bob Lanning
There is (was) a known problem with the MMIC amplifier (comprising the IF amp
into the P3) oscillating.....this instability could certainly manifest itself in what you are seeing. The guys at Elecraft sent me a replacement rear panel interface board and my prob went away Also, make certain the coax connectors are well grounded to the rear panel with the supplied star washers. Hope this helps John On Tue May 29 5:15 , Arthur Burke sent: >Is it possible the ribbon cable is as long as it is because it will need to >eventually be routed around something else to be added later? > >Art - N4PJ > > > >On Tue, May 29, 2012 at 2:10 AM, Bob Lanning [hidden email]>wrote: > >> In response to my message May 23, 2012; 3:27pm on the Elecraft P3 >> reflector Roger White W5RDW in Murphy, Texas responded off-list. He had >> the same problem I described. It was not coming from the K3 but from >> inside the P3. We both noted it started after installing the SVGA. >> >> During our investigation we boy found: >> >> 1 - the signal is about 5kHz wide >> 2 - it moves either up or down in frequency ever so slowly >> 3 - moving the VFO does not change the position of the signal - internal >> to P3? >> 4 - reach back and approach the IF signal coax between the K3 & P3 >> causes it to temporarily go away >> 5 - sometimes touching the P3 cabinet caused it to disappear >> 6 - changed out the coax but it still happens >> >> When the signal crosses the VFO frequency no sound is heard - only the >> signal being listened to. But reaching back in the proximity of the >> linking coax causes it to go away. Turning PC and other gear off has no >> effect. >> >> Roger and I spent sometime isolating the source. We found a signal was >> coupling into the IF cable inside the P3 from the ribbon cable. As you >> can see from the SVGA instruction manual the ribbon cable is so long >> that if not dressed it goes across the P3 and pushes up against the IF >> coax in the unit. >> >> When the ribbon cable is dressed by folding it tightly keeping it well >> away from the IF coax the wondering signal no longer appears. >> >> If you are having this anomaly Roger and I recommend making the change >> to the ribbon cable as shown in the two pictures below. It would be >> nice to have a shorter ribbon cable. >> >> 73, >> >> Bob - W6OPO >> Roger - W5RDW >> >> ______________________________________________________________ >> Elecraft mailing list >> Home: http://mailman.qth.net/mailman/listinfo/elecraft >> Help: http://mailman.qth.net/mmfaq.htm >> Post: [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: [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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Wow, this could be what my problem has been. In my past years as a microwave engineer, I used many of the MMIC amps when they first came out and they were difficult to tame, as they have a ton of gain at very low frequencies (lower than what they were intended to be used). I can see this may be what my problem is (was), as the signal that was creeping across the screen was large in amplitude and shaking a bunch....(aka like an oscillation). It looks like Elecraft has noted the problem. I may have temporarily solved my problem buy "finger tweaking" the assemblies by pushing, pressing, etc. but a more permanent solution will be needed eventually.
Roger W5RDW
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In reply to this post by John Klewer
I can agree with you regarding the IF oscillator oscillating since when I approach the coax it changes the conditions stopping the oscillatoin. BUT - if it was the P3's IF amplifier going into oscillation I would expect the display to freeze as no IF signal would be able to pass. That does not happen. The P3 and SVGA continue to operate as it should but has the extreneous signal displayed.
I am convinced the ribbon cable signaling was inducing a signal onto the shield of the internal IF coax. Moving the ribbon cable away from the IF coax cleared the whole problem up.
All is as it should be now.
73,
Bob - W6OPO
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I just got a message from yet another P3 user who by moving the ribbon cable away from the internal IF coax removed the extraneous phantom signal. He did NOT have the SVGA.
Elecraft - I suggest providing a shorter ribbon cable or a means to dress the cable in a straight line from front PCB to the SVGA board in the back. 73, Bob - W6OPO |
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Hi Bob,
We're taking a look at it now. A shorter ribbon cable is a possibility, but maybe there is a simple way to dress the existing cable by folding it and holding it with some sort of clip. Just thinking out loud. -Paul |
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Thats what I did...dress the cable.
Sent from my iPad On Jun 1, 2012, at 10:17 AM, "Paul Saffren N6HZ" <[hidden email]> wrote: > Hi Bob, > > We're taking a look at it now. A shorter ribbon cable is a possibility, but > maybe there is a simple way to dress the existing cable by folding it and > holding it with some sort of clip. Just thinking out loud. > > -Paul > > > -- > View this message in context: http://elecraft.365791.n2.nabble.com/P3-SVGA-interference-tp7556731p7556922.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:[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
Chuck, KE9UW
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In reply to this post by Paul Saffren N6HZ
If I may make a suggestion Paul,
Among the many obvious solutions such as Velcro strapping or nylon ties around the ribbon cable there's also the option of using a flat cable clip or mount. An example is shown on this drawing from Panduit for their model FCC-A clips; < http://www.panduit.com/groups/MPM-GAWA/documents/PartDrawing/077542.pdf> Since the ribbon cable is located close to the left side of the P3 housing an adhesive flat cable clip easily holds the cable securely away from the TMP coaxial cable on the right side of the cabinet. Another clip could be used on the right side to hold the TMP cable further away from the ribbon cable. In a pinch a short length of hook & loop material (Velcro) around the ribbon cable seems to help also but I think the TMP cable needs to be supported close to the righthand side of the cabinet with a clip or perhaps a small adhesive tie mount and nylon tie. Gary N6LRV -----Original Message----- From: [hidden email] [mailto:[hidden email]] On Behalf Of Paul Saffren N6HZ Sent: Friday, June 01, 2012 8:16 AM To: [hidden email] Subject: Re: [Elecraft] P3 SVGA interference - Hi Bob, We're taking a look at it now. A shorter ribbon cable is a possibility, but maybe there is a simple way to dress the existing cable by folding it and holding it with some sort of clip. Just thinking out loud. -Paul ______________________________________________________________ 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 Bob Lanning
I've found some adhesive clips that will allow the ribbon cable to be dressed along the left inside panel. They should be available by the end of this week, by request, no charge (EPN: E980228). All future P3 kits and factory assembled units will be getting them as well.
Thanks for all your help and suggestions. 73, Paul |
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In reply to this post by Arthur Burke
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In reply to this post by Paul Saffren N6HZ
I wonder if this discussion and suggested ribbon clips address my issue. I
acquired my K3 this past summer and then a P3 off of eBay shortly thereafter. I installed the SVGA adapter a couple months ago and I have a problem which sounds similar to what is described in this thread. For lack of a better description let me say this symptom happens only on 20Meters..... as I view my spectrum now from 14.250 to 14.350 the noise floor rests basically around S-2 across the entire band, revealing a few transmitted ham conversations, My center frequency on the scope is 14.300 and at this moment I see occasional noise peaks rising up to as high as S-5 in two or three instances approximately 10khz wide, and at times 20 khz or wider. These noise peaks are not consistent with any observed or detected human voice transmission. At times I can see a very broad band of noise on the waterfall which spans the entirety of the floating noise floor. The same observation occurs when I am tuned down in the CW portion of the band. I don't recall if this observation was present prior to adding the SVGA adapter, and I've not thought about opening the P3 to inspect or move any cables. I know this symptom can best be demonstrated with a photo, so if that would be beneficial, I will be happy to oblige. Just let me know who needs to see it. This is certainly a very annoying issue I wish to resolve. I'm open to any ideas or suggestions. Thanks, Mike, K5MP -- Sent from: http://elecraft.365791.n2.nabble.com/ ______________________________________________________________ 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 Bob Lanning
Mike,
You didn't mention if you had a large monitor connected but consider that the noise you "see" may come from it or a TV your have connected. Do you see the pattern on the P3 also? Watch the P3 screen and turn the large monitor off and see if the signal disappears. Many of them do make a lot of electrical "noise" - particularly the screen light source and very particularly plasma displays. Jim - W4RKS -------------------------------------- >I wonder if this discussion and suggested ribbon clips address my issue. I >acquired my K3 this past summer and then a P3 off of eBay shortly >thereafter. I installed the SVGA adapter a couple months ago and I have a >problem which sounds similar to what is described in this thread. . . . >I don't recall if this observation was present prior to adding the SVGA >adapter, and I've not thought about opening the P3 to inspect or move any >cables. . . . >Thanks, Mike, K5MP ______________________________________________________________ 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 mjpilgrim
Hi Mike,
Have you tried turning your monitor off? I've never had the issue you describe 73 Frank W3LPL ----- Original Message ----- From: "mjpilgrim" <[hidden email]> To: [hidden email] Sent: Saturday, February 10, 2018 8:32:03 PM Subject: Re: [Elecraft] P3 SVGA interference - I wonder if this discussion and suggested ribbon clips address my issue. I acquired my K3 this past summer and then a P3 off of eBay shortly thereafter. I installed the SVGA adapter a couple months ago and I have a problem which sounds similar to what is described in this thread. For lack of a better description let me say this symptom happens only on 20Meters..... as I view my spectrum now from 14.250 to 14.350 the noise floor rests basically around S-2 across the entire band, revealing a few transmitted ham conversations, My center frequency on the scope is 14.300 and at this moment I see occasional noise peaks rising up to as high as S-5 in two or three instances approximately 10khz wide, and at times 20 khz or wider. These noise peaks are not consistent with any observed or detected human voice transmission. At times I can see a very broad band of noise on the waterfall which spans the entirety of the floating noise floor. The same observation occurs when I am tuned down in the CW portion of the band. I don't recall if this observation was present prior to adding the SVGA adapter, and I've not thought about opening the P3 to inspect or move any cables. I know this symptom can best be demonstrated with a photo, so if that would be beneficial, I will be happy to oblige. Just let me know who needs to see it. This is certainly a very annoying issue I wish to resolve. I'm open to any ideas or suggestions. Thanks, Mike, K5MP -- Sent from: http://elecraft.365791.n2.nabble.com/ ______________________________________________________________ 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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I have the P3 attached to a HP 23" flat screen. I power off the external
monitor and still have the issue on the P3 internal monitor. I power off the monitor on two PCs in the room and power off the flat screen TV in the room. Still no relief. I removed and reconnected all connections on the back of the P3, then removed the top cover so I could attempt to change the symptoms by touching and/or moving the ribbon cable and connectors. No change. I have snapped a couple pics, so will attempt later to share those if possible. Thanks for your replies. Mike, K5MP -- Sent from: http://elecraft.365791.n2.nabble.com/ ______________________________________________________________ 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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Does the RFI go away if you remove the antenna connection to your radio?
Does it vary when you rotate your antenna? 73 Frank W3LPL ----- Original Message ----- From: "mjpilgrim" <[hidden email]> To: [hidden email] Sent: Sunday, February 11, 2018 12:04:49 AM Subject: Re: [Elecraft] P3 SVGA interference - I have the P3 attached to a HP 23" flat screen. I power off the external monitor and still have the issue on the P3 internal monitor. I power off the monitor on two PCs in the room and power off the flat screen TV in the room. Still no relief. I removed and reconnected all connections on the back of the P3, then removed the top cover so I could attempt to change the symptoms by touching and/or moving the ribbon cable and connectors. No change. I have snapped a couple pics, so will attempt later to share those if possible. Thanks for your replies. Mike, K5MP -- Sent from: http://elecraft.365791.n2.nabble.com/ ______________________________________________________________ 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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I am almost overwhelmed by all the very thoughtful suggestions. Here's what
I know so far. I had previously performed the idea of turning off all items in the room except for the radio and P3, but the reported symptom remains. I then switched my antenna switch to the grounded position, and the problem goes away......... Now my suspicion is that my rfi is created from outside my house. My antenna system consists of two end fed long wires, 90% opposed to each other, and a minimal vertical out behind the house. The RFI from all antennas is approximately equal in amplitude as I select them one at a time (with the vertical slightly less but I attribute that to the relative poor receive sensitivity on that antenna. Nonetheless, the RFI on that antenna is quite noticeable. I hesitate to bother for additional thoughts at this point, at least until I can asses what possible causes external to my house might be at play, and now to pay close attention to whether or not it changes depending on the hour of the day. For example, at first notice of this problem I sensed that everything was normal until for example, the beginning of the work day. I soon discounted that thought however, when I realized it was happening late at night (as was the case up until I shut down last night around 11pm). And it affects only 20 Meters. All other bands are viewed normally. Perhaps once I can capture and submit a picture for review here, someone might be able to make a little more sense out of what I'm trying to describe.........If I can say it this way, it reminds me of a TV commercial where folks are in a Gymnasium doing a strength regimen involving holding a rope in each hand and making it serpentine by moving the arms up and down. Only that sine wave of baseline noise moves from S-2 to as high as S-7 when using my best antenna.......... I'll try to get a picture attached later this afternoon. Thanks for the help so far. Mike, K5MP -- Sent from: http://elecraft.365791.n2.nabble.com/ ______________________________________________________________ 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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Somehow I managed to lose my last post describing the attached photo.
suffice to say my Span is set for 14.000-14.104MHZ and my cursor is tuned to 14.029, but notice that the baseline noise level while near S-2 across most of the band, shows a hump back at the center of the screen and the waterfall depicts the width of the distortion. Anyone with any suggestion beyond what I have offered, I'm all ears. Note that this phenom. occurs only on 20 Meters. Thanks, Mike K5MP <http://elecraft.365791.n2.nabble.com/file/t395115/DSCN0894.jpg> -- Sent from: http://elecraft.365791.n2.nabble.com/ ______________________________________________________________ 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 mjpilgrim
Mike,
I don't think I have seen this as a suggestion so far in the thread. It is important that you dress the cables for the SVGA option exactly as shown in the installation manual. If they do not want to stay in place, use a ty-wrap around the cables. 73, Don W3FPR On 2/11/2018 12:50 PM, mjpilgrim wrote: > I am almost overwhelmed by all the very thoughtful suggestions. Here's what > I know so far. > > I had previously performed the idea of turning off all items in the room > except for the radio and P3, but the reported symptom remains. I then > switched my antenna switch to the grounded position, and the problem goes > away......... Now my suspicion is that my rfi is created from outside my > house. My antenna system consists of two end fed long wires, 90% opposed to > each other, and a minimal vertical out behind the house. > 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 Bob Lanning
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