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{
    "url": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/UMLWDFU3QOYYS5X5JEFS3RNAAQEJ3B2I/?format=api",
    "mailinglist": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/?format=api",
    "message_id": "[email protected]",
    "message_id_hash": "UMLWDFU3QOYYS5X5JEFS3RNAAQEJ3B2I",
    "thread": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/thread/AYAQ3EJU6W2TM6JXT6RAICZ3AAZDYAIP/?format=api",
    "sender": {
        "address": "aa2tx (a) comcast.net",
        "mailman_id": null,
        "emails": null
    },
    "sender_name": "Anthony Monteiro",
    "subject": "[amsat-bb] Re: [AMSAT-BB] 145 MHz IF on V/s?",
    "date": "2008-05-17T19:39:40Z",
    "parent": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/AYAQ3EJU6W2TM6JXT6RAICZ3AAZDYAIP/?format=api",
    "children": [
        "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/4U6EFJUO76UQ7ZMLXBPMIHGCA362K3UC/?format=api"
    ],
    "votes": {
        "likes": 0,
        "dislikes": 0,
        "status": "neutral"
    },
    "content": "At 09:37 PM 5/16/2008, K & R Yoksh wrote:\n\n>  Hello Gene (and the list),\n>\n>Your question reminds me of a question I've been meaning to ask!\n>\n>My current S-band antenna is a simple integrated antenna/downconverter with\n>123 MHz IF, but I plan to install a P3E-ready dish and downconverter on my\n>crossboom this summer.\n>\n>My best downconverter is a K5GNA unit with 145 MHz IF. I wonder how it'll\n>play on mode V/s?  Can anyone comment on this?\n>\n>I also have some more 123 MHz IF units, but their NF is unknown. I'd rather\n>use my AIDC 3731 from K5GNA, even if it means reduced performance on V/s. I\n>plan to optimize for HEO operation, but I'd be happy if I could also work\n>AO-51 in mode V/s.\n\n\nHi Kyle,\n\nJust a suggestion...\n\nAll downconverters will drift with temperature. The stock AIDC 3731\nis spec'd to be within +/- 25 KHz over the temp range. I don't know\nwhat the 145 MHz units are spec'd at but I doubt that it is better.\nOther units I have seen are also around this figure and some are a\nlittle worse.\n\nThis is not much of a problem on AO-51 becuase there is a nice\nstrong carrier that is easy to find. On a linear passband like\nP3E, it can be extremely difficult to find your own downlink\nwithout QRMing the whole passband.\n\nA better solution and the one that I use, is to put a low\nnoise preamp at the antenna and put your downconverter inside\nyour house where the temp is pretty stable. I have mine in the garage\nwhich was fine for AO-40. Leaving the downconverter on all the time\nis also helpful. On AO-40, my setup was more stable than the LO\non AO-40 and I could always hear my own downlink. I used InstantTune\n(of course!) and loaded the parameters into the config file so it was\nsimple to just turn it on and work the sat. A fine tuning of around +/-1.5 KHz\nwas all that was needed to compensate for AO-40 LO drift.\n\nI used an AIDC 3731 downconverter at 123 MHz which is pretty\nsensitive but not as good as with the Down East Microwave 13ULNA preamp\nwhich is really, really! good. A second advantage of using a preamp at the\nantenna is that the downconverter sensitivity is then not very important\nso you can use almost anything, even an old Drake unit.\n\nIf you have a really long run of coax, it might be cheaper to add a second\nless expensive \"booster\" preamp and then use RG-6 coax from the preamp to the\ndownconverter. I used LMR-600 because I wanted to be able to TX on it but\nthat is overkill for just receiving P3E.\n\n\n73,\nTony AA2TX\n\n\n\n\n\n\n\n\n\n",
    "attachments": []
}