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{ "url": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/JZUJY4UJHFNMC26DDPIDSLLNJIB4ILTC/?format=api", "mailinglist": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/?format=api", "message_id": "[email protected]", "message_id_hash": "JZUJY4UJHFNMC26DDPIDSLLNJIB4ILTC", "thread": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/thread/ODX4VHJ3ET6VHGXQZ5P3DW6JMDL27PKF/?format=api", "sender": { "address": "wb4gcs (a) amsat.org", "mailman_id": "87014499e012476c8198fad186f7f963", "emails": "https://mailman.amsat.org/hyperkitty/api/sender/87014499e012476c8198fad186f7f963/emails/?format=api" }, "sender_name": "Jim Sanford", "subject": "[eagle] Re: Preliminary CAN-Do EMI Findings and Suggestions to Mitigate in the 70 cm Receiver", "date": "2007-06-15T21:09:58Z", "parent": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/HFVYGT4BHR4NPUYO4U5CNP3KJHA5T6A4/?format=api", "children": [], "votes": { "likes": 0, "dislikes": 0, "status": "neutral" }, "content": "Eventually we need to deal with the radiated noise.\n73,\nJim\n\n\nJuan Rivera wrote:\n\n>Chuck,\n>\n>I actually think that the noisy power coming out of the CAN-Do module is\n>perfect for these tests. The more I think about it the more delighted I am\n>that its there. I have no other way to generate noisy power. This is\n>great! I'll attempt to capture this noise with my oscilloscope and post it\n>in my log if I can. My scope is not feeling well these days so I may need\n>to dig up another one.\n>\n>Even if the receiver eventually receives its power from another source, we\n>need to assume that it will have switching noise on it from other payloads.\n>That's the only reasonable assumption as far as I'm concerned. The receiver\n>must be able to function in the presence of noisy power and the CAN-Do\n>module is a perfect noise source.\n>\n>Based on the above I think I'll leave the CAN-Do module alone for now and\n>see if I can add some simple filtering to kill the spurs in the IF while\n>running on the switched CAN-Do power. If it can do that then I think we\n>will be on the right track.\n>\n>Every other payload designer should take heed and plan to operate with noise\n>on their DC inputs too. This is probably a topic that needs some high-level\n>attention. Are there any power specs that describe maximum expected noise\n>levels? Perhaps a standard DC input filer should be designed and\n>incorporated in every power supply input. Why leave this up to each\n>designer? Come up with a standard filter using SMD components. I would\n>think that this filter would also work to reduce switching noise from the\n>payloads and help prevent that noise from propagating back out to other\n>payloads on the power bus. All this looks like an area that needs\n>attention.\n>\n>I'm open to advice here. All I was thinking of doing was adding about 10 uF\n>across pins 39/40 to ground, an RF choke in series, and then another 10 uF\n>cap and maybe a second smaller value to ground at the load end of that RF\n>choke. I can cobble something like that together and stick it on the PCB in\n>dead bug style. I can keep adding stages until I get rid of the noise.\n>\n>73,\n>\n>Juan\n>WA6HTP\n>\n>-----Original Message-----\n>From: Chuck Green [mailto:[email protected]] \n>Sent: Friday, June 15, 2007 7:53 AM\n>To: [email protected]\n>Cc: [email protected]; David Smith; Dave Black (Work); Dave Black (Home);\n>Samsonoff@Mac. Com; Juan.Rivera (Work)\n>Subject: Re: [eagle] Preliminary CAN-Do EMI Findings and Suggestions to\n>Mitigate in the 70 cm Receiver\n>\n>Juan,\n>\n>I have a couple of suggestions.\n>\n>Based on previous messages I presume you will not want to use the \n>switched power from the CAN-Do! regardless of the noise issue. I also \n>see that the switch transistor in the CAN-Do! is in the same area of the \n>PCB as the CAN-Do! power supply.\n>\n>1) Put a jumper between pins 2 and 3 of the switch transistor (TO-220). \n>This will bypass the switch and any noise it is picking up from the \n>power supply. This will keep the 2 amp fuse in your power source and the \n>current measurement circuit.\n>\n>2) You might also eliminate the 2 amp fuse from your power source by \n>placing a jumper from pins 1,9 of the DA15P to pin 2 of the switch \n>transistor after removing the transistor (or just cutting it's leads). \n>This will preserve the current measurement of the power going to your \n>module.\n>\n>3) You might also bypass everything by putting a jumper from pins 1,9 of \n>the DA15P to any unused user pins on that same connector (pins \n>2,3,5,10,11,12) then picking up the power from the corresponding user \n>pins on the 40 pin connector. If you do this, you should provide a \n>current measurement circuit on your module and attach it's output to one \n>of the analog input pins of the 40 pin connector.\n>\n>The above may eliminate or reduce the noise in your power source while \n>accomplishing other power source objectives.\n>\n>Chuck\n>\n>Juan Rivera wrote:\n> \n>\n>>All,\n>>\n>>I've completed a preliminary evaluation of the CAN-Do RFI problem. \n>>Please see my log for details by clicking here \n>>\n>> \n>>\n><http://www.juanr.com/pages/hobbies/ham_radio/Eagle/CAN-Do_Noise_Troubleshoo\n>ting.htm>.\n> \n>\n>>Preliminary Findings...\n>>\n>>1. The spurs seen in the receiver IF enter the receiver in two ways\n>>\n>>o As radiation from the CAN-Do inductor\n>>\n>>o Via CAN-Do module switched +14 VDC power on pins 39 and 40\n>>\n>>2. I/O line filtering appears to be unnecessary\n>>\n>>3. The switched power from the CAN-Do module pins 39 and 40 must be \n>>filtered\n>>\n>>4. The CAN-Do module will either have to be kept physically separated \n>>from any sensitive components, redesigned, shielded or a combination \n>>of the three.\n>>\n>>5. Moving the Can-Do module 2-1/4\" forward of its normal location on \n>>the receiver PCB lowers the EMI level below the noise floor.\n>>\n>>Suggestions...\n>>\n>>. Create a full size PCB for the next generation receiver and shift \n>>the RF components to the back of the board (away from the CAN-Do module.)\n>>\n>>. Add DC input filtering to the receiver\n>>\n>>73,\n>>\n>>Juan\n>>\n>>WA6HTP\n>>\n>>------------------------------------------------------------------------\n>>\n>>_______________________________________________\n>>Via the Eagle mailing list courtesy of AMSAT-NA\n>>[email protected]\n>>http://amsat.org/mailman/listinfo/eagle\n>> \n>> \n>>\n>\n>\n>_______________________________________________\n>Via the Eagle mailing list courtesy of AMSAT-NA\n>[email protected]\n>http://amsat.org/mailman/listinfo/eagle\n>\n> \n>\n\n\n", "attachments": [ { "email": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/JZUJY4UJHFNMC26DDPIDSLLNJIB4ILTC/?format=api", "counter": 2, "name": "attachment.html", "content_type": "text/html", "encoding": "iso-8859-1", "size": 6520, "download": "https://mailman.amsat.org/hyperkitty/list/[email protected]/message/JZUJY4UJHFNMC26DDPIDSLLNJIB4ILTC/attachment/2/attachment.html" } ] }