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GET /hyperkitty/api/list/[email protected]/email/HARPRU7SIDRXTV6UZAWUZWGMTOBXQGOE/?format=api
{ "url": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/HARPRU7SIDRXTV6UZAWUZWGMTOBXQGOE/?format=api", "mailinglist": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/?format=api", "message_id": "000f01c8f7e2$e35076b0$0b09a8c0@zeus", "message_id_hash": "HARPRU7SIDRXTV6UZAWUZWGMTOBXQGOE", "thread": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/thread/ZJD4DDZD3EAUCKG7SWIAKVHMC5PFRL32/?format=api", "sender": { "address": "sv1bsx (a) yahoo.gr", "mailman_id": null, "emails": null }, "sender_name": "SV1BSX", "subject": "[amsat-bb] Re: Re polarity control box - again", "date": "2008-08-06T16:38:38Z", "parent": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/ZJD4DDZD3EAUCKG7SWIAKVHMC5PFRL32/?format=api", "children": [], "votes": { "likes": 0, "dislikes": 0, "status": "neutral" }, "content": " Hi Gus,\n\nif you mean the FIG.68 in VHF/UHF manual (page 8.28), I can't see something\nwrong.\nI have made this system a few years ago and I did not notice any problem.\n\nPosition 5 for RHCP has a Matching stub (L/4 75 Ohm) in series with 135'\nYagi and\na Matching stub (L/4 75 Ohm) + a Phasing-stub (L/4 50 Ohm) in series with\n45' Yagi.\n\nPosition 6 for LHCP: a Matching stub (L/4 75 Ohm) + a Phasing-stub (L/4 50\nOhm)\nin series with 135' Yagi and a Matching stub (L/4 75 Ohm) in series with\n45' Yagi.\n\nWhere is the L/2 (as you pointed out) ??? I can't see it.\n\nThe 135' Yagi on LHCP is fed with 2 stubs in series,\nbut the first one is L/4 50 Ohms and acts as \"Phasing stub\" and the second\nis L/4 75 Ohms \"Matching stub\". They have different \"Z\" each one, so\nthere are not 2 pieces L/4 50 Ohms = L/2 50 Ohms.\n\n\n73, Mak SV1BSX\n\n\n\n----- Original Message ----- \nFrom: \"Angus\" <[email protected]>\nTo: <[email protected]>\nSent: Wednesday, August 06, 2008 6:06 PM\nSubject: [amsat-bb] Re polarity control box - again\n\n\n> Hi all, its me again, sorry.\n> OK got the 2mtr polarity control box working and very pleased, except for\n> one very small item.\n> LHCP never seemed to me to be 90 degrees out of phase with RHCP, never had\n> the large drop in signal I expected.\n> OK time for a bit or research and looked in to my VHF/UHF manual and found\n> the pages and guess what, the design we have been using is wrong, or so I\n> think, please correct me if I am wrong.\n> OK both yagis have a 1/4 wave 75 ohm matching system to allow the system\n> back to work with 2 x 50 ohm yagis in parallel, in case anyone forgets, so\n> for Vertical both yagis fed in phase, for Horizontal the 135 degrees yagi\n> is fed with a 1/2 wave of 50 ohm line to delay it by 180 degrees, no\n> problems so far.\n> For RHCP the 45 degrees yagi is fed with a 1/4 wavelength of 50 ohm delay\n> line and again no problems.\n> NOW HERE'S THE RUB!\n> For LHCP we feed the 135 degrees yagi with a 1/4 wavelength of 50 ohm\n> line, woops the system has a 1/2 wavelength of 50 ohm line!\n> So instead of feeding as we should we are feeding it to make it simpler\n> than it should be. Hence I was never happy that LHCP was never quite 90\n> degrees out with RHCP.\n> So quite possibly we are going to get some form of strange oval type of\n> polarity anyone take a guess at its true nature, I may have a play around\n> with one of the antenna programs and see what comes out.\n> Am I wrong completely on this or is it the better to have it off a little\n> on LHCP to get the other 3 polarities correct?\n> Sorry for boring some of you.\n> regards\n> Gus M0IKB\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\n", "attachments": [] }