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{
    "url": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/KKVDWGWAKH2M5ZMKIUNAA4RRXJJA62UA/?format=api",
    "mailinglist": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/?format=api",
    "message_id": "1BCDCDCF3A8448BD9E995B16F2FAA128@parents",
    "message_id_hash": "KKVDWGWAKH2M5ZMKIUNAA4RRXJJA62UA",
    "thread": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/thread/5TIEHTUCUKWLTZGMTNFQ3TZYG5LEOKDL/?format=api",
    "sender": {
        "address": "ka3hsw (a) att.net",
        "mailman_id": "afface7d7e8049fda539552165bdde78",
        "emails": "https://mailman.amsat.org/hyperkitty/api/sender/afface7d7e8049fda539552165bdde78/emails/?format=api"
    },
    "sender_name": "George Henry",
    "subject": "[amsat-bb] Re: HO-68 Linear Transponder - Newbie Questions",
    "date": "2009-12-29T22:23:02Z",
    "parent": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/5TIEHTUCUKWLTZGMTNFQ3TZYG5LEOKDL/?format=api",
    "children": [],
    "votes": {
        "likes": 0,
        "dislikes": 0,
        "status": "neutral"
    },
    "content": "With your 2-radio setup, you should definitely leave your uplink frequency \nfixed, and tune only the downlink.  Unless you have full computer control \nfor doppler, this is the \"One True Rule\" anyway:  tune only the higher of \nthe two frequencies, where the doppler shift is greatest (about 9 kHz at \n435).  (If you ever get on VO-52, note that it has a VHF downlink and a UHF \nuplink, so you would tune the uplink there instead.)\n\nRemember that the transponder is INVERTING:  you must uplink on LSB, and \nlisten to the downlink on USB.  Also, the higher your downlink frequency is \nin the passband, the LOWER your uplink frequency will be.  CW is generally \nfound in the lower half of the passband (435.715 - 435.740) and voice in the \nupper half (435.740 - 435.765).  Therefore, you should pick a downlink \nfrequency above .740, and set your uplink radio to the corresponding \nfrequency (the same amount DOWN from 145.950, the center of the uplink \npassband, as your downlink frequency is ABOVE 435.740, ie, an uplink of \n145.940 for a downlink of 435.750)  Pick a clear frequency, but don't go too \nhigh up, as most voice activity tends to stay pretty close to the center. \nFor convenience, you might want to make up a little nomograph or chart that \nhas the downlink frequencies on one line/column, and their corresponding \nuplink frequencies on another.\n\nAs far as power goes, the general rule has always been that your downlink \nshould be no stronger than the beacon.  That way, you're not tripping the \nAGC & knocking down someone else's signal.  The FCC rule is, the minimum \npower necessary.  Others have reported that 5 watts to an Arrow is \nsufficient.\n\nTransmit either a slow voice count or a string of CW dits or V's while \ntuning your receiver around the predicted downlink frequency until you hear \nyourself.  Early in a pass, while the bird is coming toward you, it'll be \nhigher, and drift downward as the pass progresses.  Call CQ, and listen for \nsomeone coming back.  They probably won't be right on your downlink \nfrequency, as doppler shift will be different at their location than at \nyours, so you'll have to tune your downlink to them.  Hopefully, they will \ntune theirs to match yours.  You'll get the hang of it pretty quickly.\n\nGood luck, & hope to hear you on the birds!\n\nGeorge, KA3HSW\n\n\n\n\n----- Original Message ----- \nFrom: \"Mike Benonis\" <[email protected]>\nTo: \"BB\" <[email protected]>\nSent: Tuesday, December 29, 2009 1:41 PM\nSubject: [amsat-bb] HO-68 Linear Transponder - Newbie Questions\n\n\n> I'm a relative satellite newbie, and hence I don't have a base station set \n> up.  I do have a 2m SSB rig and an HT capable of SSB reception up at 435 \n> MHz, as well as an Arrow antenna.  With that in mind, does anyone have any \n> tips for making contacts via the linear transponder on HO-68?  Other than \n> keeping my antenna pointed in the direction of the bird/rotated to avoid \n> fades, how much do I need to compensate for doppler on the transmit and \n> receive rigs?    If I only tweak the RX rig, is that acceptable?  Also, \n> how much power should I use?  Thanks for any advice this list might have!\n>\n> 73's de Mike KI4RIX\n>\n>\n>\n> Best regards,\n>\n> Mike Benonis\n> [email protected]\n> KI4RIX\n\n",
    "attachments": []
}