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{
    "url": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/AJQDC6TDZ67AACLKCKLZ5ZNAM7YTXMZN/?format=api",
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    "message_id": "CAGkenmf6aiUeL12en7fCOqdDoUouw6tecXfQZiUaa0Z9rbxbUg@mail.gmail.com",
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    "thread": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/thread/QTC73QG72QMHQ3MQL555RYZNBUTJHKQ6/?format=api",
    "sender": {
        "address": "rbutler (a) tsss.org",
        "mailman_id": "7d1973824b814588ab990efab2d162b7",
        "emails": "https://mailman.amsat.org/hyperkitty/api/sender/7d1973824b814588ab990efab2d162b7/emails/?format=api"
    },
    "sender_name": "Ryan Butler",
    "subject": "Re: [amsat-bb] Alpha Spid Rotator",
    "date": "2020-06-06T01:27:47Z",
    "parent": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/ATXVX7MDBMGOCW3UWNADNBR4IO7IOAS4/?format=api",
    "children": [
        "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/BN23WJ6YHXWL5U3GFX3UOD7XE6QK3NCW/?format=api"
    ],
    "votes": {
        "likes": 0,
        "dislikes": 0,
        "status": "neutral"
    },
    "content": "What's everyone using for rotor cable to feed the Alpha Spid?\n\nRyan, NF0T\n\n\nOn Wed, Jun 3, 2020 at 1:45 PM Leffke, Zachary via AMSAT-BB <\[email protected]> wrote:\n\n> Hi Dave,\n> We use a lot of the RAS/HR and Big-RAS/HRs at VT in our ground station and\n> on other projects.  My biggest recommendation is if you don't absolutely\n> need the resolution, don't get the high resolution variants (0.2 deg\n> resolution).  It uses a quadrature encoder feedback mechanism that is\n> highly susceptible to EMI corruption leading to 'dropped counts' and a\n> general slew of problems related to calibration and reliable pointing\n> knowledge.  We have constantly battled this problem since day 1 of the VTGS\n> and still don't have reliable resolution for the problem (but enough\n> band-aid solutions to keep limping along and periodic trips out to the\n> tracking station to recalibrate).  The smaller Ras/HRs seem to generally do\n> better on the feedback front (still high resolution with the quadrature\n> feedback) for some reason, but we typically use those in 'deployable'\n> scenarios and the feedback cabling is much shorter (maybe 20ft or so)....so\n> not necessarily an apples to apples comparison with the perm\n>  anently installed Big-RAS/HRs that have longer feedback cables (roughly\n> 100-200 ft depending on which antenna stack we're talking about) and\n> generaly seem to be more prone to issues.  I also personally own a Ras/HR\n> (smaller one) with the high res feedback and a 2.4m solid dish mounted on\n> it.  It can handle the load just fine with proper counterweighting and so\n> far I haven't had any feedback issues (roughly 50ft feedback\n> cable)....knock on wood.\n>\n> The 'non high resolution' (low resolution?...its still accurate to about 1\n> deg) variants use plain ol' potentiometer feedback.  I don't have direct\n> experience with them, but have reports from some colleagues that they\n> haven't had any serious or repetitive issues with pointing calibration\n> (some radio astronomers in Physics dept are using one with a 2m dish).  (I\n> think that one uses a different controller than the MD-01 that we use, but\n> I think the MD-01 or MD-02 could handle either type of feedback).\n>\n> Other 'warnings' include realizing they have no mechanical stops in\n> azimuth (they do in elevation, roughly at 180 deg limits).  That said, it\n> isn't really a problem as most controllers work reliably with 'software\n> limits' and the MD-01s at least have timeouts that help if things 'go\n> wonky' with feedback.  There are some cases though that result in the\n> perfect storm of corrupted feedback that goes undetected by the MD-01 that\n> could lead to a bad azimuth situation; in our case we monitor antenna\n> motion on a camera, so are able to mitigate that scenario with human\n> intervention (and our custom control software looks for 'impossible speeds'\n> as reported by the MD-01 positions that further helps mitigate that when\n> the feedback goes awry).\n>\n> Mechanically, they have done very well for us with the double-worm gear\n> design, imperceptible gear slip (if any).  I've heard of folks having\n> mechanical failures, but I don't know the details, and that hasn't been my\n> experience.  As an example, at the height of 'performance' I was able to\n> reliably track multiple S-Band downlinks with a 3m mesh dish antenna with\n> no discernible negative effects due to point errors or 'jiggle' in the\n> system (part of that is the ramp up, also part the counterweighting).  In\n> the 5 or so years we've been running them, we haven't had any major\n> mechanical malfunctions (knock on wood), and part of that is probably due\n> to periodic maintenance (re-greasing and such), which I've done at least\n> once (can't remember exactly, maybe twice in that 5 year window).  Part of\n> that is also the fact that we tend to use the yagi stacks with a lighter\n> load a lot more than the larger dish systems, I might be singing a\n> different tune if the dishes were used daily.\n>\n> The MD-01 controller (and MD-02s as well for non-rackmount variants) does\n> have some nice ramp-up/ramp-down features, particularly useful for larger\n> systems (like our 4.5m dish).  I do wish the API documentation for the\n> MD-01 command interface was a little better...but we've been able to work\n> through it (for example, they changed the protocol a bit in a relatively\n> recent firmware update that broke compatibility with our software and\n> presumably things like rotctl in hamlib, but I think that has all been\n> fixed/updated).  The API issue might not be a problem for most folks not\n> interested in writing their own software, or if you are using a different\n> controller.  The overall documentation situation is a little 'meh' in\n> general as there have been a lot of versions and such released and they are\n> on different websites run by different folks.....but at least there is\n> documentation at all and a little reading and experimentation is usually\n> enough to get what you need, and the basics such as th\n>  e wiring diagram hasn't really changed over the years.\n>\n> I can't directly speak to the SatPC32 question because we don't use it.\n> Other than that firmware update hiccup, I'd be willing to bet it works fine.\n>\n> Bottom Line:  When they work, they seem to work well, at least in my\n> experience.  If I were going to buy one today for personal use, I'd get one\n> with the potentiometer feedback if the intended use is for something like a\n> few Yagis and if I were planning a more permanent installation.  If I were\n> going to buy something for VT/work with a better funding source than my\n> 'hobby budget' I'd probably look for something better, like M2 products\n> (pretty significant jump in price point though).\n>\n> I hope this helps.\n> -Zach, KJ4QLP\n>\n> --\n> Research Associate\n> Aerospace & Ocean Systems Lab\n> Ted & Karyn Hume Center for National Security & Technology\n> Virginia Polytechnic Institute & State University\n> Work Phone: 540-231-4174\n> Cell Phone: 540-808-6305\n>\n> -----Original Message-----\n> From: AMSAT-BB <[email protected]> On Behalf Of Dave via AMSAT-BB\n> Sent: Wednesday, June 3, 2020 1:20 PM\n> To: AMSAT BB <[email protected]>\n> Subject: [amsat-bb] Alpha Spid Rotator\n>\n> Is anyone using an Alpha Spid az/el rotor? If so how do you like it? Would\n> you recommend it over the Yaesu's and are there any issues using it with\n> SatPC32?\n>\n> Thanks,\n>\n> Dave\n> N2OA\n> _______________________________________________\n> Sent via [email protected]. AMSAT-NA makes this open forum available\n> to all interested persons worldwide without requiring membership. Opinions\n> expressed\n> are solely those of the author, and do not reflect the official views of\n> AMSAT-NA.\n> Not an AMSAT-NA member? Join now to support the amateur satellite program!\n> Subscription settings: https://www.amsat.org/mailman/listinfo/amsat-bb\n> _______________________________________________\n> Sent via [email protected]. AMSAT-NA makes this open forum available\n> to all interested persons worldwide without requiring membership. Opinions\n> expressed\n> are solely those of the author, and do not reflect the official views of\n> AMSAT-NA.\n> Not an AMSAT-NA member? Join now to support the amateur satellite program!\n> Subscription settings: https://www.amsat.org/mailman/listinfo/amsat-bb\n>\n",
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