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{
    "url": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/XM3FEWKSF4ZBXNHMLRXWRQQO3GCWC2GW/?format=api",
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    "message_id": "00be01c8a35d$4595f280$0200a8c0@Tanguray",
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    "thread": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/thread/XM3FEWKSF4ZBXNHMLRXWRQQO3GCWC2GW/?format=api",
    "sender": {
        "address": "rogerkola (a) aol.com",
        "mailman_id": "8323dbe496014835b5bd2be9b5ff6f66",
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    "sender_name": "Roger Kolakowski",
    "subject": "[amsat-bb]  Fw: [amsat-ne]  Cornell Satellite Team Needs Help",
    "date": "2008-04-21T03:10:32Z",
    "parent": null,
    "children": [
        "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/YW2EPIQ6LBKEIXOWIZS4ZVVJAG3X4JS7/?format=api"
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        "status": "neutral"
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    "content": "\n----- Original Message ----- \nFrom: \"Nathaniel S. Parsons\" <[email protected]>\nTo: <[email protected]>\nSent: Sunday, April 20, 2008 9:32 PM\nSubject: [amsat-ne] Cornell Satellite Team Needs Help\n\n\n> Hello everyone,\n> \n> I am a student at Cornell University, and a member of the Cornell\n> University Satellite Project Team (http://cusat.cornell.edu).  We are\n> preparing for a launch in June, but problems were found with our RF\n> system, so I'm trying to solicit help from those with experience,\n> expertise, and/or equipment related to spacecraft\n> communication/antenna design on the amateur 70-cm band. If you have\n> any or all of this, please read on.\n> \n> Some backstory: last year, we won the University Nanosat-4\n> competition, and the prize was a free launch.  Right now, we are\n> aiming to be put on the next launch of the Falcon 1 rocket by SpaceX.\n> Both parts of the satellites have been assembled, and are undergoing\n> further testing with the AFRL in Albuquerque.  While that seems to be\n> going along well, our latest test of the RF system doesn't look good,\n> and we don't have the equipment or expertise to correctly diagnose the\n> problem or find a solution, nor do we have much time.  So, I apologize\n> if this email is rather disjointed, but there are many things going on\n> at once. I'll be glad to clarify anything I can. Also, I think it\n> would be best if you assumed that we don't know anything about\n> anything, because something that is obvious to you may not be very\n> obvious to us.\n> \n> The problem surfaced on Friday, when we performed a ridge test to\n> verify that our RF system was adequate, and found out that it is not.\n> We had a the satellite's antenna attached to a structural prototype of\n> the satellite, and brought it to a hill roughly 4km from our ground\n> antenna. We stuck attenuators on the ground station, between the\n> antenna and the pre-amp in order to simulate the path loss we would\n> experience in space (LEO, 330x685, 9.1 degree inclination), and\n> transmitted from the satellite.  By our calculations, we needed\n> roughly 57 dB of attenuation in order to be confident that we could\n> hear the satellite while it was at the edge of the horizon, but we\n> lost signal after 10 dB. It is possible we made mistakes in the design\n> or construction of the satellite's antenna, or in the configuration of\n> the ground station, so I would greatly appreciate if you could look\n> over what we have and did, and see if you could point out what we've\n> done wrong, what we can do to further test this, and what potential\n> solutions are. If anyone is in the Ithaca area, I would be more than\n> willing to show you our setup.\n> \n> On each satellite, we have two square loop antennas made of 12-gauge\n> copper wire, 8.3125 cm per side, corner fed.  At the feed point of the\n> antenna, we have a matching circuit as follows:\n> \n> (antenna)-----------------------+----C2---+--------------TX/RX\n>      |_________________C1______L________Ground\n> \n> C1=56uF\n> C2=33uF\n> L=10.7nH\n> \n> According to our EZNEC model, this comes pretty close to matching\n> impedence with our 50-ohm, RG316  coax, 1/2 wavelength long, which\n> feeds into a Kenwood TH-D7AG, modified to fit in a metal box suitable\n> for flight. For the test, we didn't use the flight radio, but\n> connected the same antenna to an unmodified TH-D7 held outside the\n> prototype structure (if that has any significance). Since the best SWR\n> meter we have is an MFJ 269 we don't really know how to use, we have\n> not been able to verify that the antenna + matching circuit perform\n> the same as in the simulation, or have the same impedance.  I just now\n> found someone at Cornell with a network analyzer, and I hope he will\n> let me use it. What else should we do to test the antenna? Did we even\n> choose the 'right' kind of antenna for what we want to do?\n> \n> On the ground station side, we have the following equipment:\n> \n> Antenna: M2 436CP30 70-cm, circularly polarized Yagi\n> Coax: RG-8, 50 ohm\n> Pre-amp: KP-1-440 70 cm in-shack GaSa FET Pre-amplifier (Oops, just\n> found out from ARRL Handbook we need a mast-mounted one. What\n> mast-mounted pre-amps are available for 70-cm? Can we simply weather\n> proof what we have and stick it on the antenna's mast?)\n> Transceiver: Kenwood TS-2000\n> TNC: Kantronics KAM-XL\n> Rotator: G-5500 with GS-232B controller\n> Rotator control software: NOVA for Windows\n> Radio control software: Ham Radio Deluxe\n> \n> Unfortunately we're not entirely sure about how to fully use all of\n> our equipment, or if we're using them correctly.  It's possible that\n> we have something off and we aren't able to fully step back and see\n> all the 'little things.'  Would it be possible for someone to take a\n> look at what we have and show us best practices and/or help us with a\n> sanity check?  We can flip through several different manuals and check\n> different websites for help but it might be better to have some\n> grizzled experience working alongside us.\n> \n> Thanks for any advice or help you can provide.  We're excited to be\n> working on this and learning as we go along, but we could really use a\n> guided push towards success.\n> \n> 73\n> -Nate Parsons\n> KC2SVI\n> _______________________________________________\n> Via the AMSAT-NE mailing list courtesy of AMSAT-NA\n> [email protected]\n> http://amsat.org/mailman/listinfo/amsat-ne\n> \n",
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