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{
    "url": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/BWEY7FI6ZZODV5KHTQKTFUOSEGJULRPO/?format=api",
    "mailinglist": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/?format=api",
    "message_id": "[email protected]",
    "message_id_hash": "BWEY7FI6ZZODV5KHTQKTFUOSEGJULRPO",
    "thread": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/thread/FPQ3IOK7YULKQEKW67HZNRPRRJI64S2V/?format=api",
    "sender": {
        "address": "Mat_62 (a) charter.net",
        "mailman_id": "171b40085c2e4ecebefde213375137db",
        "emails": "https://mailman.amsat.org/hyperkitty/api/sender/171b40085c2e4ecebefde213375137db/emails/?format=api"
    },
    "sender_name": "Michael",
    "subject": "[amsat-bb] Re: inquiry about homebrew az-el systems",
    "date": "2013-02-24T04:22:04Z",
    "parent": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/LNTUCMQ5VLO6A3MTPAME7DF36332GDTF/?format=api",
    "children": [],
    "votes": {
        "likes": 0,
        "dislikes": 0,
        "status": "neutral"
    },
    "content": "A few years back I built the SAEBRETrack system shown here \nhttps://sites.google.com/site/marklhammond/saebrtrack.  It's based \naround a BASIC stamp.  I built the version used to control the OR-360 \nrotators but those have become very scarce and worth their weight in \ngold if you can find them. My point is this though, if you open up an \nOR-360 you find a surprisingly small \"540\" DC motor driving the gear \ntrain  and direction is controlled by voltage polarity. Positioning is \nby  potentiometer feedback. There are probably better ways to do it than \na BASIC stamp these days but the concept of driving DC motors to control \nlightweight arrays has crossed my mind a few times as well.\nMichael, W4HIJ\n\nOn 2/23/2013 9:25 PM, Gus wrote:\n> Given the shortage of LEO birds, exactly how much antenna do we need \n> to rotate?\n>\n> Hams operate satellite successfully with hand-held antennas, which \n> have low wind-loading and are light in weight.\n>\n> With R/C servos available producing 6½ ft. lb of torque for less than \n> 150 bucks, I'm surprised a light weight, portable, DC-operated \n> satellite system complete with antennas and AZ/EL rotors  hasn't \n> materialized before now.\n>\n> On 02/23/2013 07:59 PM, Samudra Haque wrote:\n>> Hi, about two years ago, I started a design for a robotics class \n>> project of\n>> a AZ-EL rotator controller system, and a hardware package for the \n>> mechanism\n>> for rotating an antenna in any direction subject to mechanical stops. \n>> The\n>> system would have been able to handle regular and flip modes. I \n>> didn't do\n>> anything more than calculations, and moved on to building a classroom\n>> instructional robot then.\n>>\n>> Lately, as I am setting up (K3GWU, the George Washington University \n>> Amateur\n>> Radio Club and Research Station) I find that the price of az-el systems\n>> such as G5500 + Yaesu AZ-EL rotors are expensive, and are not typically\n>> available on an affordable basis on Ebay or eham.net etc. Well, of \n>> course,\n>> expensive is a relative term, for a student hobby organization, it's \n>> a lot,\n>> and I guess for small ham operators it is also moderately expensive.\n>>\n>> This may be a frequently asked topic: does any one have experienced with\n>> (tested) kit designs for AZ-EL rotors that can be made with parts from\n>>   current suppliers ? I know there are a number of controller \n>> designs, but I\n>> am interested to know if there are any options for suppliers of the\n>> required gears/motors etc.\n>>\n>> I have located several large AC motors / DC motors at my university\n>> mechanical engineering workshop, but they are not all guaranteed the \n>> same\n>> specs. I now realize if I do embark on a actual design process with my\n>> model/simulation/hardware, it would be nice to build several of these \n>> all\n>> at once to share the development cost over the production run, and \n>> ensure\n>> those who want a cheap AZ-EL system can get one. Otherwise the \n>> production\n>> cost of one heavy duty system is going to be quite high.\n>>\n>> I hope some of you may have suggestions for me, both (+) and (-) or \n>> perhaps\n>> (~) in nature. I thought amsat / amateur radio folks have a common \n>> need to\n>> encourage homebrew activity to keep their brain cells in working \n>> condition?\n>>\n>> I'm opening this question up to the national US audience, and welcome \n>> any\n>> discussion on the challenges of making the ever-so-important\n>> azimuth-elevation rotor. I've studied some of the alternatives: Alliance\n>> U100 and Yaesu G-5500. I think we can do better in 2013. But ideally, to\n>> allow the wide adoption of AMSAT ground stations, what price point would\n>> the system have to be to make it worth building ?\n>>\n>> 73 de N3RDX\n>> George Washington University\n>>\n>>\n>>\n>\n>\n\n",
    "attachments": []
}