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GET /hyperkitty/api/list/[email protected]/email/X6PEJYWX6OPKVFXJ2SNOSLWB5BGDKSM5/
{ "url": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/X6PEJYWX6OPKVFXJ2SNOSLWB5BGDKSM5/", "mailinglist": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/", "message_id": "[email protected]", "message_id_hash": "X6PEJYWX6OPKVFXJ2SNOSLWB5BGDKSM5", "thread": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/thread/ECHI2GIW4O5MQA3OUPAVB745SYDC57IB/", "sender": { "address": "jfloyd (a) es.vccs.edu", "mailman_id": "70d469d92b644ab383aaa9118343282a", "emails": "https://mailman.amsat.org/hyperkitty/api/sender/70d469d92b644ab383aaa9118343282a/emails/" }, "sender_name": "John Floyd", "subject": "[amsat-bb] Re: AO-7 V/A Transponder (Mode A)", "date": "2011-12-08T22:40:07Z", "parent": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/ECHI2GIW4O5MQA3OUPAVB745SYDC57IB/", "children": [], "votes": { "likes": 0, "dislikes": 0, "status": "neutral" }, "content": "Is anyone adjusting elevation on the 10 meter side?\n________________________________________\nFrom: [email protected] [[email protected]] on behalf of [email protected] [[email protected]]\nSent: 08 December 2011 14:14\nTo: [email protected]\nSubject: [amsat-bb] AO-7 V/A Transponder (Mode A)\n\nOperational linear transponder satellites have dwindled to only two: VO-52\nand AO-7. The latter, now 37 years old, spends approximately half its\noperating time on the V/A transponder, or what we used to call Mode A:\n145.85-145.95 MHz uplink, 29.4-29.5 MHz downlink.\n\nUnfortunately, activiity on the V/A transponder is quite low compared with\nwhat it was in the 1970s. Today, as then, much of this problem can be\nattributed to the V/A transponder's relatively weak downlink signal. In the\n1970s, however, many users were able to solve this problem and work DX through\nthis transponder out to nearly 8,000 km.\n\nHow did they do it? As one of those 1970s users, I'll tell you: low-noise\npreamplifiers and good 10-meter antennas. In 2011, most modern radios have\nenough sensitivity that an external 29 MHz preamplifier should not be\nrequired. That leaves the antenna. Most satellite users wouldn't think of\noperating Mode U/V without good antennas. The 29 MHz band is no different.\n\nAs any successful 1970s Mode A user can attest, a good 10-meter beam is by\nfar the best choice. For best results, it should be pointed at the horizon,\nnot elevated. Why? For most users at temperate zone latitudes, AO-7's\nelevation angle will be 10 degrees or less about half the time it is in range,\nand 30 degrees or more only about 10% of the time. During that 10%, the\ninverse-square law of distance will keep signals strong despite AO-7 being\noutside the beam's major lobe..\n\nAs in HF operation, the beam should be mounted as high above ground as\npossible. My friend Ben, W2BXA (now SK), with his beam at 20 meters, was able[\nto work stations up to 300 km farther away than I could with mine at only 10\nmeters. That is a large part of the reason why Ben held Satellite DXCC No.\n1 while mine is No. 13.\n\nIf you cannot put up a beam, a rotary dipole is perhaps the next best\nchoice, again mounted as high as possible. If you cannot do that either, try a\nground plane antenna, mounted so as to be clear of all obstructions. No\nmatter what your specific circumstances, put up the best 10-meter antenna you\ncan.\n\nLet's use and enjoy BOTH transponders of AO-7!\n\n73 Ray W2RS\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": [] }