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GET /hyperkitty/api/list/[email protected]/email/5HGJFDJ3ML2BOFAWZ5RRNCSIO6MBPHXL/?format=api
{ "url": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/5HGJFDJ3ML2BOFAWZ5RRNCSIO6MBPHXL/?format=api", "mailinglist": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/?format=api", "message_id": "4320416054294C8A9CFDF44DD898E2CB@kc6uqh", "message_id_hash": "5HGJFDJ3ML2BOFAWZ5RRNCSIO6MBPHXL", "thread": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/thread/I3SPJQZ2NAQC7QWDU7ECPFSYPEBSYIW5/?format=api", "sender": { "address": "kc6uqh (a) cox.net", "mailman_id": "d9201820d18047e4a2772c86bda5e111", "emails": "https://mailman.amsat.org/hyperkitty/api/sender/d9201820d18047e4a2772c86bda5e111/emails/?format=api" }, "sender_name": "Art McBride", "subject": "[amsat-bb] Re: G-5500 stuck problem", "date": "2009-01-02T18:01:09Z", "parent": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/ACQV56VPWY73LZS5WV33GCOLP4XW2VYK/?format=api", "children": [], "votes": { "likes": 0, "dislikes": 0, "status": "neutral" }, "content": "To All,\nAntenna rotator motors are capacitor run types. All induction motors shift\nthe phase of the current. The current is nearest to being in phase only when\nthe rotor is locked. An unloaded motor draws almost no power as the current\nis out of phase with the voltage. As the antenna rotators age, the run\ncapacitor looses capacity causing a reduction in torque from the motor. This\ncapacitor is in the control box, is low cost and the first thing that should\nbe replaces if the rotator is slowing down. Typically the run capacitor only\nlasts for 10 years of service. TV antenna rotators did not last that long\nbut the Amateur Radio antenna rotators will often outlast the run capacitor.\n\n\nArt, KC6UQH \n\n\n\n\n-----Original Message-----\nFrom: [email protected] [mailto:[email protected]] On\nBehalf Of Greg D.\nSent: Thursday, January 01, 2009 11:09 PM\nTo: [email protected]; [email protected]\nSubject: [amsat-bb] Re: G-5500 stuck problem\n\n\nHi Kevin,\n\nSo, my take-away here is that it's not the stall itself that is the problem;\nthe motor is practically designed to self-destruct. Simply running the\nrotor back and forth enough times will do the same thing. In fact, probably\nworse, given the higher draw.\n\n\nOne thing just occurred to me... AC current measurements assume a specific\nphase relationship between voltage and current - power factor, I think they\ncall it. This is a highly inductive load, and the phase-shift capacitor\nthrows another unknown into the puzzle. I wonder if the two measurements\nyou took are real? It could be that you think that the running current is\nhigher, when it may just be a measurement error. How were they measured?\n\nGreg KO6TH\n\n\n> From: [email protected]\n> To: [email protected]\n> Date: Thu, 1 Jan 2009 20:51:47 -0800\n> Subject: [amsat-bb] Re: G-5500 stuck problem\n> \n> Hi Greg,\n> these transformers and motors are rated for intermittent duty so getting\nthem stuck and left that way kills them, if memory serves \n> they pull about 1.7 amps running, and drop to about 1.2 amps stalled,\n1.2amps x 25v = 30 watts and over time that heat builds up and \n> fries the windings.\n> \n> It's just a oddity of this particular type of ac motor that it behaves\nthis way, if it was another type or a dc motor you would see \n> the current rise that you expected and fuses would pop.\n> \n> I found this out when I was making a add on card to my LVB tracker to\nreplace the G-5500 control box, I thought I would be slick \n> and add one of the PPTC resettable fuses on the motors, so I needed to\nknow the running current and locked current so I could pick \n> the right one, I was also surprised when the current dropped a little\ninstead of going up, and then doing some reading on the web \n> about dual winding AC motors that use a capacitor to phase shift the\nother winding explained why this happens.\n> \n> 73\n> Kevin WA6FWF\n> \n> \n> ----- Original Message ----- \n> From: \"Greg D.\" <[email protected]>\n> To: <[email protected]>; <[email protected]>\n> Sent: Thursday, January 01, 2009 7:04 PM\n> Subject: RE: [amsat-bb] Re: G-5500 stuck problem\n> \n> \n> \n> Ha, really... Thanks, I was \"sure\" it was the other way around.\n> \n> So, if the current drops a little on a jam, why would it burn up either\nthe transformer or motor?\n> \n> Greg KO6TH\n> \n> \n> > From: [email protected]\n> > To: [email protected]\n> > Date: Thu, 1 Jan 2009 18:42:15 -0800\n> > Subject: [amsat-bb] Re: G-5500 stuck problem\n> >\n> > Hi Greg,\n> > Actually you need to measure the current while it is moving, then if\nit drops a little then its a jam, if it goes to zero then\n> > its the limit switch.\n> >\n> > I know this goes against reasoning, you expect a locked motor to pull\nmore current, but these are split winding AC motors with a\n> > capacitor and they act differently.\n> >\n> > This is also why when you get a cable snag you burn up the motor or the\ntransformer or both before you blow the fuse, that fuse I\n> > think just saves you from a mis-wired or shorted cable.\n> >\n> > 73\n> > Kevin WA6FWF\n> >\n> . \n> \n> _______________________________________________\n> Sent via [email protected]. Opinions expressed are those of the author.\n> Not an AMSAT-NA member? Join now to support the amateur satellite program!\n> Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb\n\n_________________________________________________________________\nLife on your PC is safer, easier, and more enjoyable with Windows VistaR. \nhttp://clk.atdmt.com/MRT/go/127032870/direct/01/\n_______________________________________________\nSent via [email protected]. Opinions expressed are those of the author.\nNot an AMSAT-NA member? 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