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{
    "url": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/HFVYGT4BHR4NPUYO4U5CNP3KJHA5T6A4/?format=api",
    "mailinglist": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/?format=api",
    "message_id": "001601c7af61$95a6e5e0$0301a8c0@Shop",
    "message_id_hash": "HFVYGT4BHR4NPUYO4U5CNP3KJHA5T6A4",
    "thread": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/thread/ODX4VHJ3ET6VHGXQZ5P3DW6JMDL27PKF/?format=api",
    "sender": {
        "address": "juan-rivera (a) sbcglobal.net",
        "mailman_id": null,
        "emails": null
    },
    "sender_name": "Juan Rivera",
    "subject": "[eagle] Re: Preliminary CAN-Do EMI Findings and Suggestions to\tMitigate in the 70 cm Receiver",
    "date": "2007-06-15T15:26:44Z",
    "parent": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/B42J7V53UNKCX2CRM3JMDV7VT5S32HAN/?format=api",
    "children": [
        "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/4DXO4B7SSUBYJ42DCGPRXWHNU2N5T67R/?format=api",
        "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/JZUJY4UJHFNMC26DDPIDSLLNJIB4ILTC/?format=api"
    ],
    "votes": {
        "likes": 0,
        "dislikes": 0,
        "status": "neutral"
    },
    "content": "Chuck,\n\nI actually think that the noisy power coming out of the CAN-Do module is\nperfect for these tests.  The more I think about it the more delighted I am\nthat its there.  I have no other way to generate noisy power.  This is\ngreat!  I'll attempt to capture this noise with my oscilloscope and post it\nin my log if I can.  My scope is not feeling well these days so I may need\nto dig up another one.\n\nEven if the receiver eventually receives its power from another source, we\nneed to assume that it will have switching noise on it from other payloads.\nThat's the only reasonable assumption as far as I'm concerned.  The receiver\nmust be able to function in the presence of noisy power and the CAN-Do\nmodule is a perfect noise source.\n\nBased on the above I think I'll leave the CAN-Do module alone for now and\nsee if I can add some simple filtering to kill the spurs in the IF while\nrunning on the switched CAN-Do power.  If it can do that then I think we\nwill be on the right track.\n\nEvery other payload designer should take heed and plan to operate with noise\non their DC inputs too.  This is probably a topic that needs some high-level\nattention.  Are there any power specs that describe maximum expected noise\nlevels?  Perhaps a standard DC input filer should be designed and\nincorporated in every power supply input.  Why leave this up to each\ndesigner?  Come up with a standard filter using SMD components.  I would\nthink that this filter would also work to reduce switching noise from the\npayloads and help prevent that noise from propagating back out to other\npayloads on the power bus.  All this looks like an area that needs\nattention.\n\nI'm open to advice here.  All I was thinking of doing was adding about 10 uF\nacross pins 39/40 to ground, an RF choke in series, and then another 10 uF\ncap and maybe a second smaller value to ground at the load end of that RF\nchoke.  I can cobble something like that together and stick it on the PCB in\ndead bug style.  I can keep adding stages until I get rid of the noise.\n\n73,\n\nJuan\nWA6HTP\n\n-----Original Message-----\nFrom: Chuck Green [mailto:[email protected]] \nSent: Friday, June 15, 2007 7:53 AM\nTo: [email protected]\nCc: [email protected]; David Smith; Dave Black (Work); Dave Black (Home);\nSamsonoff@Mac. Com; Juan.Rivera (Work)\nSubject: Re: [eagle] Preliminary CAN-Do EMI Findings and Suggestions to\nMitigate in the 70 cm Receiver\n\nJuan,\n\nI have a couple of suggestions.\n\nBased on previous messages I presume you will not want to use the \nswitched power from the CAN-Do! regardless of the noise issue. I also \nsee that the switch transistor in the CAN-Do! is in the same area of the \nPCB as the CAN-Do! power supply.\n\n1) Put a jumper between pins 2 and 3 of the switch transistor (TO-220). \nThis will bypass the switch and any noise it is picking up from the \npower supply. This will keep the 2 amp fuse in your power source and the \ncurrent measurement circuit.\n\n2) You might also eliminate the 2 amp fuse from your power source by \nplacing a jumper from pins 1,9 of the DA15P to pin 2 of the switch \ntransistor after removing the transistor (or just cutting it's leads). \nThis will preserve the current measurement of the power going to your \nmodule.\n\n3) You might also bypass everything by putting a jumper from pins 1,9 of \nthe DA15P to any unused user pins on that same connector (pins \n2,3,5,10,11,12) then picking up the power from the corresponding user \npins on the 40 pin connector. If you do this, you should provide a \ncurrent measurement circuit on your module and attach it's output to one \nof the analog input pins of the 40 pin connector.\n\nThe above may eliminate or reduce the noise in your power source while \naccomplishing other power source objectives.\n\nChuck\n\nJuan Rivera wrote:\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<http://www.juanr.com/pages/hobbies/ham_radio/Eagle/CAN-Do_Noise_Troubleshoo\nting.htm>.\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",
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