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{
    "url": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/W3J5GE64PBVSBEFT6YBT5VEXXF7XH6GX/",
    "mailinglist": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/",
    "message_id": "[email protected]",
    "message_id_hash": "W3J5GE64PBVSBEFT6YBT5VEXXF7XH6GX",
    "thread": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/thread/W3J5GE64PBVSBEFT6YBT5VEXXF7XH6GX/",
    "sender": {
        "address": "frankwoolfe (a) optusnet.com.au",
        "mailman_id": null,
        "emails": null
    },
    "sender_name": "Frank Woolfe",
    "subject": "[amsat-bb]  Re; Circular switching",
    "date": "2009-06-26T23:42:56Z",
    "parent": null,
    "children": [],
    "votes": {
        "likes": 0,
        "dislikes": 0,
        "status": "neutral"
    },
    "content": "Hi Jan PE0SAT, my emails are not getting through to you so I'll post here,\n\n \n\nI have had some success so far,\n\n \n\nI've made up two lengths of RG213 with 1/4 wave lengths of 75ohm cable on\neach end. These are to run from the coax relay to the 145mhz Yagi's as the\nARRL drawing suggests. N type connectors are used on each end of these\ncables.\n\n \n\nI've tested this as a phasing harness and achieved around 30dB return loss\nthat's with the 75ohm transformer ends in a T piece and 50ohm loads on the\nend of each cable.\n\n \n\nThis was tested on my HP8920 using a 50Mhz to 1000Mhz Narda coupler and am\nhappy with the results, so the phasing harness as it is, is centered on\n145mhz with a VSWR of 1.06:1.\n\n \n\nNext is the delay line, this has got to be an impedance of between 104 to\n110ohms, as the antennas are between 52 to 55ohms now this is going to be\nhit and miss, as you can't get 105ohm coax. However, you can get 93ohm and\nwhat I'm thinking is to remove the center conductor of the coax and replace\nit with a smaller diameter conductor this should raise the impedance of the\ncoax hopefully to around 105-110 ohms, thus achieving the required impedance\nof the delay line which is called for in that circuit.\n\n \n\nThe 93 ohms is just too low and I've found with my testing so far it's\nbetter to be on the high side of impedance than the low. The 93 ohms seems\nto look like near enough to 75ohms and acts like another transformer\nsection.\n\n \n\nSo I'll continue on and keep you in the loop on success or failure.\n\n \n\nThanks for your mail and Best 73's\n\n \n\nFrank VK5KV...\n\n \n\n \n\n \n\n",
    "attachments": []
}