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{
    "url": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/MBJ33AWHTAVVAUY5VC4XTVLEXLDFG35F/?format=api",
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    "message_id": "008c01c849c6$523f1fc0$0200a8c0@kc6uqh",
    "message_id_hash": "MBJ33AWHTAVVAUY5VC4XTVLEXLDFG35F",
    "thread": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/thread/VORDXUAQMKXQGXHYOVL7HHTD5ES2ZMWK/?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": "kc6uqh",
    "subject": "[amsat-bb] Re: 435 offset yagi phasing",
    "date": "2007-12-29T02:55:50Z",
    "parent": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/VORDXUAQMKXQGXHYOVL7HHTD5ES2ZMWK/?format=api",
    "children": [
        "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/IJAVS22K6MX4IKIU6APPGS5275U2IQPU/?format=api"
    ],
    "votes": {
        "likes": 0,
        "dislikes": 0,
        "status": "neutral"
    },
    "content": "Andrew,\nYes that is correct with one exception that a 50 ohm, 1/2 wave section needs \nto be inserted for the opposite rotation in one antenna. This is switched in \nand out with a coax switch or relay. The 1/4 wave sections do the matching \nand both offer the same delay so there is no phase difference to the \nantennas. As the antennas are 1/4 wave offset one leads by 90 degrees. \nadding a 180 degree delay will cause that antenna to lag by 90 degrees and \nhence the opposite rotation.\n\nGood luck with the project. Learning by doing is the best way!\n\nArt,\nKC6UQH\n----- Original Message ----- \nFrom: \"Andrew Rich\" <[email protected]>\nTo: \"Amsat-Bb@Amsat. Org\" <[email protected]>\nSent: Friday, December 28, 2007 3:25 AM\nSubject: [amsat-bb] 435 offset yagi phasing\n\n\n> Hi\n>\n> I have had good success with just one yagi of an offset crossed array I am\n> building.\n>\n> http://wa5vjb.com/yagi-pdf/cheapyagi.pdf\n>\n> I will add the other elements shortly.\n>\n> I am not ready to tackle the phasing part.\n>\n> I hope I have this right.\n>\n> 1. The yagi's are offset, by 90 degrees so that is the offset already.\n> 2. Both yagis's should then have the same length of coax coming from each\n> one.\n> 3. Both yagi's will require a 1/4 wavelength of 75 ohm coax for each feed.\n> 4. Remebering that the velocity factor is 2/3 in coax cable, or the speed \n> of\n> light 200 instead of 300.\n> 5. Both 75 ohm feeds then join at a tee, the result of the 50 ohm antenna\n> and 70 ohm feed giving around 120 ohm\n> 6. By tee'ing the two together, this should present around 50 ohm, \n> required\n> for the main feedline.\n>\n> Does that sound right ?\n>\n> ( 200/435 MHz ) /4 = 11.49 cm for each feed to the tee junction of 75 ohm\n> cable.\n>\n>\n> ----------------------------------------------------------------------------\n> Andrew Rich VK4TEC\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",
    "attachments": []
}