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    "url": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/X6ABPZ7CIUAPAPYAEKSI5Z6I2IKPMPE4/?format=api",
    "mailinglist": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/?format=api",
    "message_id": "[email protected]",
    "message_id_hash": "X6ABPZ7CIUAPAPYAEKSI5Z6I2IKPMPE4",
    "thread": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/thread/RQX4DLDIYY3MVVVNFRFO357N5UXLTUIQ/?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: Jim's comments",
    "date": "2007-07-19T00:33:50Z",
    "parent": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/IE3TOMSY6MUSB327BYBGKWY546FVOW3K/?format=api",
    "children": [],
    "votes": {
        "likes": 0,
        "dislikes": 0,
        "status": "neutral"
    },
    "content": "All:\nI'm not going to say much on this, because I want the discussion to \nflow, and then for John to make recommendations that we can peer reivew \nre the redesign.\n\nI will say this:\nJuan makes an interesting proposal, which will solve much of the EMI \nissue for weak signal receivers.  I still think we need to reduce, as \nmuch as reasonably possible, the noise generated, radiated, and \nconducted by the CAN-Do! widget under all postulated uses in Eagle.  \nThere are many reasons why this is just a good idea.\n\n73,\nJim\[email protected]\n\nJuan Rivera wrote:\n\n> Jim and gang,\n>\n>  \n>\n> I have a bit of new information for you regarding the CAN-Do step-down \n> converter:\n>\n>  \n>\n> The Maxim 1836 step-down converter is designed to deliver output \n> currents of up to 125 milliamps, but in this circuit it is only \n> supplying 11 mills.  The spec sheet shows that the efficiency and the \n> switching frequency both drop off badly at that low output current.  \n> It's pretty clear that this IC is not the ideal choice for this very \n> small load.  I can think of several alternatives:\n>\n>  \n>\n> 1)       Replace the noisy switching downconverter with a linear \n> regulator and remove all traces of generated EMI\n>\n> 2)      Find another more suitable step-down converter and design a \n> new circuit and a new PCB\n>\n> 3)      At least for the 70 cm Receiver, disconnect the CAN-Do \n> step-down converter and power the CAN-Do module from the +5 volt \n> receiver supply. It shouldn't even notice another 11 mills.\n>\n>  \n>\n> Let's assume for the moment that we end up with a two-compartment \n> enclosure.  What if we just disable the CAN-Do module's step-down \n> converter and create a small PCB that would attach to the 40-pin \n> header and be the home for the power supplies for whatever was in the \n> other side of the enclosure - in this case the receiver analog \n> circuitry.  The CAN-Do module would get its power from that little \n> board and so would the receiver.  In the case of this receiver we \n> could put all the power supplies on a PCB about the size of a large \n> postage stamp.\n>\n>  \n>\n> Don, KD6IRE amplifies on my idea and suggests that the digital \n> compartment be placed off to the side - just wide enough to allow the \n> existing CAN-Do module to fit.  The main compartment would then be an \n> 'L' shape, but with access to the front panel.  All RF and IF I/O from \n> the rear compartment would come up the leg on the \"L\", with SMA \n> connectors all located on one side of the CAN-Do D connector.\n>\n>  \n>\n> Again speaking only from the perspective of the 70 cm receiver, I \n> think this would require the least amount of redesign and result in a \n> pretty clean passband.  The benefits would be:\n>\n>  \n>\n> 1)       No major modifications to the CAN-Do module required (same \n> PCB and same connector)\n>\n> 2)      No connectors out the side or the top creating wiring headaches\n>\n> 3)      No more 5 kHz radiated or conducted CAN-Do EMI inside the \n> enclosure or propagated back up the DC power lines (5 kHz spurs \n> completely gone)\n>\n> 4)      Moves the 157 kHz receiver switching power supply to the \n> separate compartment in the front on that little daughter board and \n> gets rid of that spur in the passband\n>\n> 5)      Minor modifications to the enclosure - just another internal \n> sheet metal piece\n>\n> 6)      The Receiver PCB form factor could remain the same or it could \n> change to the \"L\" shape, depending on what works best.\n>\n>  \n>\n> This still leaves the issue of flex unresolved and this suggestion \n> might not work for every project but it seems like it might be worth \n> trying.\n>\n>  \n>\n> 73,\n>\n>  \n>\n> Juan\n>\n>  \n>\n> P.S.  Maxim 1836 link à \n> http://datasheets.maxim-ic.com/en/ds/MAX1836-MAX1837.pdf\n>\n>  \n>\n\n\n",
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