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{ "url": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/EKYG43L3F5SAJLBAI2U437TELN4LB77Y/", "mailinglist": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/", "message_id": "000d01c7b159$21f79d70$0301a8c0@Shop", "message_id_hash": "EKYG43L3F5SAJLBAI2U437TELN4LB77Y", "thread": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/thread/PFUGZ676R3TJDCZDCVW676TCFQKJQ2C2/", "sender": { "address": "juan-rivera (a) sbcglobal.net", "mailman_id": null, "emails": null }, "sender_name": "Juan Rivera", "subject": "[eagle] Re: 70 cm Receiver IF Spurs - Problem Solved", "date": "2007-06-18T03:31:13Z", "parent": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/6SZTN2EK5UZYKWHOE77FVEZNX6FZ5E4E/", "children": [], "votes": { "likes": 0, "dislikes": 0, "status": "neutral" }, "content": "CAN-Do guys,\n\n \n\nCan someone supply me with a suitable shielded replacement for the L3\ninductor? I'll be happy to swap it out and report back.\n\n \n\nJuan\n\n \n\n _____ \n\nFrom: Jim Sanford [mailto:[email protected]] \nSent: Sunday, June 17, 2007 7:35 PM\nTo: [email protected]\nCc: 'Chuck Green'; 'David Smith'; 'Dave Black (Work)'; 'Dave Black (Home)';\[email protected]; 'Samsonoff@Mac. Com'; 'Juan.Rivera (Work)'\nSubject: Re: [eagle] Re: 70 cm Receiver IF Spurs - Problem Solved\n\n \n\nTeam:\nI ABSOLUTELY agree with Juan's assertion that\n... it needs to be free of radiated and conducted EMI in both directions. \n\nWe need to resolve these issues, and then issue such resolution as a\nrequirement.\n\nSize of incoming power conductor is a spacecraft issue, that we need to get\ninto the Black Forest notes and subsequent requirements.\n\nEliminating the radiated noise is a CAN-Do! issue and should be solved --\nespecially if it is as simple as replacing a radiating inductor with a\nshielded inductor.\n\nIn my professional life, I've seen a similar situation, where such an\ninductor in a VERY sensitive instrumentation system was picking up noise, a\nfatal flaw. Replacing the one component with a shielded equivalent solved\nthe problem.\n\nWe should at least TRY such an approach. .. .\nJuan, I'd like you to do the swap and then give us before and after plots\nand analysis. That will conclusively prove or disprove the issue.\n\nThanks & 73,\nJim\[email protected]\n\n\nJuan Rivera wrote: \n\nChuck,\n\n \n\nAt least in this particular case jumpering across the switch didn't work.\n(See my log for today on Eaglepedia.)\n\n \n\nSince the CAN-Do module is such an imbedded and pervasive component in\nEagle, I think it needs to be free of radiated and conducted EMI in both\ndirections. It's a great little interface but I'm afraid it has some very\nserious shortcomings at the moment:\n\n \n\nConducts noise back towards the power source where it can impact other loads\non the same power bus (one ohm of resistance out there was enough to screw\nup the receiver.)\n\nProvides a noisy +14 to its load (the noise went right through the receiver\nlike fat through a goose and ended up in the IF as spurs.)\n\nRadiates EMI that can adversely affect sensitive circuitry at a distance of\nover two inches from the rear of the PCB\n\n \n\nAttempting to mitigate those problems will put a huge burden on every\npayload and the adverse impact might not be fully known until integration\nand test, if then. Trying to go back and band-aid something like this after\nall the payloads come together would be a very bad corner to get backed\ninto. You could do what I did and sacrifice 2 inches of space inside every\nmodule chassis, or you could try to build a two-section chassis and filter\nthe lines passing through the bulkhead, adding complexity. But that doesn't\naddress the potential impact to another payload from the spikes that are\npropagated back towards the common +14 bus.\n\n \n\nI would expect that every receiver, block up or down converter, transmitter,\nor amplifier will be impacted by this noise in a similar way. In my opinion\nthis is a global problem that needs a global solution. If the CAN-Do module\ncan be made EMI-free, or meet a yet to be determined EMI spec, then all of\nthe payloads teams can start their design with a known environment.\n\n \n\nIf the CAN-Do module is not modified then I think the only safe thing to do\nis to build each payload so it can function using CAN-Do switched +14 volt\npower (the receiver can't in the Rev-A configuration.) If your payload can\nfunction with that noisy +14, without any adverse impact, then it is\nprobably a pretty well protected circuit and should be fairly immune to\nwhatever noise is added to the source by conducted EMI from other loads on\nthe power bus. It just seems simpler and cleaner to fix the problem at the\nsource.\n\n \n\nI have an idea for a noise generator that I will stick on my log... This\ncould be the go/no go test for each payload. I'll go sketch it up and get\nit uploaded by about 2000 Pacific Time.\n\n \n\n73,\n\n \n\nJuan\n\n \n\n \n\n-----Original Message-----\nFrom: Chuck Green [mailto:[email protected]] \nSent: Sunday, June 17, 2007 5:51 PM\nTo: [email protected]\nCc: [email protected]; Bill Ress; Dave Black (Home); Dave Black (Work); Dave\nhartzell; David Smith; Don Ferguson; Juan.Rivera (Work); Samsonoff@Mac. Com\nSubject: Re: [eagle] 70 cm Receiver IF Spurs - Problem Solved\n\n \n\nHi Juan,\n\n \n\nOne of the purposes of the CAN-Do! was to provide a standard interface \n\nso that a module couldn't do something nasty and take out the entire \n\nsatellite. So custom mods to the CAN-Do! are not allowed. Having said \n\nthat, we have always assumed that a jumper across the CAN-Do! power \n\nswitch would be installed for those modules that needed to be powered up \n\nno-matter-what.\n\n \n\nChuck\n\n \n\nJuan Rivera wrote:\n\n> Chuck,\n\n> \n\n> I don't want to tear into the CAN-Do module. I feel like it is a loaner\nand\n\n> not mine to modify. It would be interesting to disconnect the switch and\n\n> the current monitor from the CAN-Do power input and move it to those user\n\n> pins as you suggest. That might just work, but I also know they don't\nwant\n\n> to have multiple versions of the module floating around and this would be\n\n> one.\n\n> \n\n> We also can't loose sight of the radiated noise from that inductor. I can\n\n> see signs of EMI if it gets within 2 inches of the sensitive areas of the\n\n> receiver.\n\n> \n\n> 73,\n\n> \n\n> Juan\n\n> \n\n> \n\n> 73,\n\n> \n\n> Juan\n\n> \n\n> -----Original Message-----\n\n> From: Chuck Green [mailto:[email protected]] \n\n> Sent: Sunday, June 17, 2007 9:18 AM\n\n> To: [email protected]\n\n> Subject: Re: [eagle] 70 cm Receiver IF Spurs - Problem Solved\n\n> \n\n> Hi Juan,\n\n> \n\n> I am impressed with your testing and analysis. \n\n> \n\n> I find it curious that you were unable to filter the power from the \n\n> CAN-Do! . But switching noise is notorious for being difficult to \n\n> filter. So maybe that is something to just forget. But in a total \n\n> system (satellite) it may not be possible to forget. We may need to \n\n> find a way to filter the power for sensitive modules even if not using \n\n> power from the CAN-Do! ; in which case, such a filter may also filter \n\n> the noise from the CAN-Do! .\n\n> \n\n> If your analysis is correct, and it certainly seems to be, then it would \n\n> also seem possible to remove the switch from the CAN-Do! (not just \n\n> bypass it) and rout your clean power source through the CAN-Do! current \n\n> measurement circuit thus saving having to do this in the module.\n\n> \n\n> Great work! And thanks.\n\n> \n\n> Chuck\n\n> \n\n> \n\n> \n\n> Juan Rivera wrote:\n\n> \n\n>> Hi Chuck,\n\n>> \n\n>> Bad news I'm afraid. See my report for details... I've sent out a link\n\n>> \n\n> to\n\n> \n\n>> the group.\n\n>> \n\n>> 73,\n\n>> \n\n>> Juan\n\n>> \n\n>> -----Original Message-----\n\n>> From: Chuck Green [mailto:[email protected]] \n\n>> Sent: Saturday, June 16, 2007 8:57 AM\n\n>> To: [email protected]\n\n>> Cc: [email protected]; David Smith; Dave Black (Work); Dave Black (Home);\n\n>> Samsonoff@Mac. Com; Juan.Rivera (Work)\n\n>> Subject: Re: [eagle] 70 cm Receiver IF Spurs - Problem Solved\n\n>> \n\n>> Hi Juan,\n\n>> \n\n>> This is fantastic! \n\n>> \n\n>> Please try one more experiment. Pass the module current through the \n\n>> current measuring circuit on the CAN-Do! while bypassing the switch \n\n>> transistor (you could just short across the switch transistor) and see \n\n>> if the problem reappears. \n\n>> \n\n>> If you end up having to use the user pins, you will need to add current \n\n>> measuring circuitry to your module. While this is no big deal, its one \n\n>> more thing you might not have to do.\n\n>> \n\n>> Chuck\n\n>> \n\n>> Juan Rivera wrote:\n\n>> \n\n>> \n\n>>> All,\n\n>>> \n\n>>> \n\n>>> \n\n>>> The 70 cm Receiver spur problem has been solved. Click here \n\n>>> \n\n>>> \n\n>>> \n\n>\n<http://www.juanr.com/pages/hobbies/ham_radio/Eagle/CAN-Do_Noise_Troubleshoo\n\n> \n\n>> ting.htm> \n\n>> \n\n>> \n\n>>> for details.\n\n>>> \n\n>>> \n\n>>> \n\n>>> 73,\n\n>>> \n\n>>> \n\n>>> \n\n>>> Juan\n\n>>> \n\n>>> WA6HTP\n\n>>> \n\n>>> ------------------------------------------------------------------------\n\n>>> \n\n>>> _______________________________________________\n\n>>> Via the Eagle mailing list courtesy of AMSAT-NA\n\n>>> [email protected]\n\n>>> http://amsat.org/mailman/listinfo/eagle\n\n>>> \n\n>>> \n\n>>> \n\n>> \n\n>> \n\n>> \n\n> \n\n> \n\n> \n\n> \n\n \n\n\n\n\n\n _____ \n\n\n\n \n_______________________________________________\nVia the Eagle mailing list courtesy of AMSAT-NA\[email protected]\nhttp://amsat.org/mailman/listinfo/eagle\n \n\n\n", "attachments": [ { "email": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/EKYG43L3F5SAJLBAI2U437TELN4LB77Y/", "counter": 2, "name": "attachment.html", "content_type": "text/html", "encoding": "us-ascii", "size": 40014, "download": "https://mailman.amsat.org/hyperkitty/list/[email protected]/message/EKYG43L3F5SAJLBAI2U437TELN4LB77Y/attachment/2/attachment.html" } ] }