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{
    "url": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/54RNAGA6MPPBKF5DSHHVSQOGWSSVMOE3/?format=api",
    "mailinglist": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/?format=api",
    "message_id": "000301c96995$a884aa40$f98dfec0$@com",
    "message_id_hash": "54RNAGA6MPPBKF5DSHHVSQOGWSSVMOE3",
    "thread": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/thread/YLYLAYGOHSO7ZVENZE33LYVC6ER2Y26B/?format=api",
    "sender": {
        "address": "tim (a) timtapio.com",
        "mailman_id": null,
        "emails": null
    },
    "sender_name": "Tim Tapio",
    "subject": "[amsat-bb] Re: Fw: ELK or ARROW",
    "date": "2008-12-29T09:13:04Z",
    "parent": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/WJ56RFR4D4QF2AJXNYFFPYY6ZWAYTFFJ/?format=api",
    "children": [],
    "votes": {
        "likes": 0,
        "dislikes": 0,
        "status": "neutral"
    },
    "content": "Bruce,\n\nPutting on a preamp worked wonders (I used a Hamtronics). I'd go in the\nbackyard with it and I put the Arrow on a tripod. It worked out well but I\ndid have desense problems. I finally went to separate antennas, put them on\nan MFJ tripod and bought a rotor from Radio Shack. I pointed the antennas up\nat a 30 degree elevation and had my best success this way.\n\nThe boom was regular schedule 40 pvc and had quite a bit of sag, the 2 meter\nantenna was vertical and the 70 cm was horizontal. I then rearranged the\nantennas to the opposite orientation (I don't remember what my justification\nwas) but I never did get a chance to compare them, life events made\noperating take a back seat.\n\nI still had desense issues so I finally tossed in a Comet diplexer that I\nhad in the box of goodies....(I don't have a \"junk box\".\n\nI also had about a 10' run of RG-8x so system losses didn't amount to much.\n\nJust my experience but I recommend use of a diplexer as a filter for the\nreceive....terminate the 2 meter side (I used an old Ethernet 50 ohm\nterminator).\n\nGood luck!\n\nTim T  K4SHF  #35580\n\n\n\n-----Original Message-----\nFrom: [email protected] [mailto:[email protected]] On\nBehalf Of Bruce Robertson\nSent: Sunday, December 28, 2008 10:41 PM\nTo: Bob K0NR (email list)\nCc: [email protected]\nSubject: [amsat-bb] Re: Fw: ELK or ARROW\n\nI had a great time experimenting with homebrew handheld dual-band antennas\nfor satellite work before I bought an arrow antenna. It is important to note\nthat, as in so many applications, higher antenna gain is not necessarily\nbetter. Think of it as a narrower flashlight\nbeam: are you sure you can point the beam directly at the bird? If you lose\ntrack of it, how easy will it be to find it again? Moreover, a longer boom\nmeans a heavier antenna, and it is amazing how heavy a handheld antenna\nbecomes after 10 minutes!\n\nSo I'd say that it is just important in our discussions of antenna gain to\ndiscuss pattern. If the handheld satellite antenna's gain is improved by\nmaking a pencil-thin front lobe and some side lobes, that's really no good:\nyou'll be too frustrated trying to find the bird.\n\nThere are, however, some aspects of the entire receiving system that we can\nimprove. This diplexer number is a bit alarming. I expect it is possible to\ndo better.\n\nAnother trick commonly used on home stations is to put a preamp at the\nantenna output. The low-noise preamp improves the overall noise figure of\nthe system, and compensates for the 'down-stream' losses if put before them,\ni.e., at the antenna.\n\nAs it happens, I've been thinking about how it might be possible to\nsuper-charge an arrow antenna with a 435 preamp. I have a small ARR\nswitching preamp handy, but it needs 12v. Some sort of AA battery pack with\na charge-pump circuit might do the trick of small enough. Will the added\nweight on my wrist be worth the improved reception on 435?\nOnly experimentation will tell.\n\n73, Bruce\nVE9QRP\n\nOn Sun, Dec 28, 2008 at 3:22 PM, Bob K0NR (email list) <[email protected]>\nwrote:\n> [email protected] wrote:\n>> It seems improving the 2.4 dB of insertion loss of the diplexer would \n>> be a better strategy (although not necessarily easy in the space \n>> available) than attempting to modify what is very mechanically sound\nantenna.\n>>\n>> 73,\n>> Joe kk0sd\n>>\n>>\n>\n>    I am surprised that the duplexer/diplexer (take your pick) has that\n>    much loss.\n>    Has anyone verified this via a direct measurement (such as via a\n>    network analyzer)?\n>\n>    Bob K0NR\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_______________________________________________\nSent via [email protected]. Opinions expressed are those of the author.\nNot an AMSAT-NA member? Join now to support the amateur satellite program!\nSubscription settings: http://amsat.org/mailman/listinfo/amsat-bb\n\n",
    "attachments": []
}