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{
    "url": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/5R2AAKZ6UAZLSIJFKNWGQJK6BO3CTA6K/",
    "mailinglist": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/",
    "message_id": "[email protected]",
    "message_id_hash": "5R2AAKZ6UAZLSIJFKNWGQJK6BO3CTA6K",
    "thread": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/thread/JQ2BU73CTOVGDNAALSGAN2BVYZSZGJHZ/",
    "sender": {
        "address": "tosca005 (a) tc.umn.edu",
        "mailman_id": "ddd1e012a31843ce830c5bc7888b5fea",
        "emails": "https://mailman.amsat.org/hyperkitty/api/sender/ddd1e012a31843ce830c5bc7888b5fea/emails/"
    },
    "sender_name": "John P. Toscano",
    "subject": "[amsat-bb] Re: RIT for FT-726R?",
    "date": "2007-10-18T23:03:03Z",
    "parent": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/SB34EU5HHFPUR37VVCWA4D5QDVTYLCLK/",
    "children": [],
    "votes": {
        "likes": 0,
        "dislikes": 0,
        "status": "neutral"
    },
    "content": "Scott Townley wrote:\n\n> Now someone is likely to correct me on that last statement...but even \n> radios with tracking VFOs, track at a Hz-per-Hz rate, don't they?  My \n> IC-821 does...so if you manually tune, even with the VFOs in track, one \n> link is a little off because they need to track at 3:1 (at least for VU and \n> UV modes).\n\nYes, the VFO's track on a Hz-per-Hz basis, but this is not an error, it \nis by design. Remember, tracking of the VFO's has nothing to do with \nDoppler correction, where the amount of Doppler shift is proportional to \nfrequency. The tracking of the VFO's has to do with positioning yourself \nwithin the passband of the uplink and downlink. On a linear transponder, \nonce you are tuned in, moving 1 Hz on the uplink requires a 1 Hz move on \nthe downlink (either in the same direction for non-inverting \ntransponders, or in the opposite direction for inverting transponders) \nto stay tuned in. So if you hear your uplink coming down on the downlink \nin a quiet part of the passband, and tune the tracked VFO's to a new \nfrequency where someone else is looking for a QSO, the downlink of your \nuplink should have followed you to the new frequency unless you took so \nlong that the Doppler shift has changed significantly. But unless you \ntuned extremely slowly, you should be at least pretty close. Every so \noften, you have to adjust the frequency of the higher link without \nchanging the frequency of the lower link to adjust for Doppler. On the \nFT-847, you either use the sub-tune knob to do that, or briefly un-lock \ntracking, re-tune, and re-lock tracking. And if the transponder is \ninverting and the ratio of frequencies is roughly 3:1 (mode VU or UV), \nthe shifting Doppler is moving the two frequencies in opposite \ndirections and so the net change in Doppler adjustment you need to make \nis closer to 2:1 than 3:1. Other modes have other ratios of changing \nDoppler, but at least for short periods of time when the net change in \nDoppler is small, a 1 Hz shift in tx causes a 1 Hz shift in rx, even \nmode V/S where the rx:tx ratio is over 16:1.\n\n73 de WØJT\n",
    "attachments": []
}