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{
    "url": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/DJXTQATYSB5PHM73ZS2AWITV3ZAGT23N/?format=api",
    "mailinglist": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/?format=api",
    "message_id": "[email protected]",
    "message_id_hash": "DJXTQATYSB5PHM73ZS2AWITV3ZAGT23N",
    "thread": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/thread/MQCGIL5GVCJA2YNYLAIV2VBKM2WX67N6/?format=api",
    "sender": {
        "address": "aa2tx (a) comcast.net",
        "mailman_id": null,
        "emails": null
    },
    "sender_name": "Anthony Monteiro",
    "subject": "[amsat-bb] Re: Coaxial line question",
    "date": "2010-01-24T16:26:02Z",
    "parent": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/MQCGIL5GVCJA2YNYLAIV2VBKM2WX67N6/?format=api",
    "children": [],
    "votes": {
        "likes": 0,
        "dislikes": 0,
        "status": "neutral"
    },
    "content": "Hi Luc,\n\nI am assuming you meant 7/8\" Heliax.\n\n45' of Heliax and a short LMR400 jumper will have around\n0.6 dB of loss on 70cm so that just adds 0.6 dB to\nthe noise figure of your preamp (i.e. ~1.0 dB to ~1.6 db.)\nWith even a modest gain antenna, you probably will not be\nable to notice any difference on a satellite downlink.\n\nOn 2 meters, even less difference.\n\n73,\nTony AA2TX\n\n---\n\n\nAt 05:04 AM 1/24/2010, Luc Leblanc wrote:\n>Yes again a returning question \"preamp at the tower or near the shack\"\n>\n>I will have to do soon some maintenance work on my satellite \n>antennas tower. I planned to use 2 heliax 1/78\" 45'  individual line. Each\n>line will be terminated by high quality 2psp coaxial microwave \n>switch feeding UHF and VHF antennas. I don't know if i can move my VHF and\n>UHF preamp at the other end near the shack where each line will \n>enter the house on short LMR 400 run 10 feet max?\n>\n>I know the theory says the best place to put a preamp is at the \n>antenna but with the very low loss on the Heliax coaxial line,  is in the\n>real world there will be any significant degradation in the noise \n>figures who will be really noticeable?\n>\n>Note: If the relays are introducing too much loss i can feed the \n>antenna directly from them on the 8' run on LMR-400 directly on the female\n>N type heliax connector.\n>\n>P.S. One commercial microwave technician is telling me that i will \n>be able to see difference only on labs spectrum/signal generator in\n>short i will be unable to tell any difference due to the short \n>length of my coaxial line. He told me he's playing with 300 to 600 feets of\n>lines in his day to day work and 45 feet heliax run are nearly \n>consider as jumper line in his world...\n>\n>\n>\"-\"\n>\n>\n>Luc Leblanc VE2DWE\n>Skype VE2DWE\n>www.qsl.net/ve2dwe\n>DSTAR urcall VE2DWE\n>WAC BASIC CW PHONE SATELLITE\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",
    "attachments": []
}