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{ "url": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/3WIEZSGMO32TAU5SDYNPME34FNCTQA2G/", "mailinglist": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/", "message_id": "[email protected]", "message_id_hash": "3WIEZSGMO32TAU5SDYNPME34FNCTQA2G", "thread": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/thread/3WIEZSGMO32TAU5SDYNPME34FNCTQA2G/", "sender": { "address": "jonny290 (a) gmail.com", "mailman_id": "bed0432ae6e64c0493fa6343553c3746", "emails": "https://mailman.amsat.org/hyperkitty/api/sender/bed0432ae6e64c0493fa6343553c3746/emails/" }, "sender_name": "Jonny 290", "subject": "[amsat-bb] Station not coming together - the full post (sorry for\trepost, reply to this)", "date": "2007-03-07T02:52:57Z", "parent": null, "children": [ "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/ITDBJQ2VKUZQGU5I5NLBPTX3DTMN3TE6/" ], "votes": { "likes": 0, "dislikes": 0, "status": "neutral" }, "content": "LONG LONG LONG post ahead.\n\nOK, the situation is: I'm building up a satellite station to get familiar\nwith LEO sats and to get ready for the phase 3E fun to start soon. Here's my\nstation, and I'll post my thoughts after that.\n\nThe \"too long, didn't read\" version: I've built good antennas, fed them with\ngood feedlines and into a supposedly good receiver, but I just can't keep\nsolid copy on LEO birds, and cannot get a QSO. I am jealous of the\n\"Satellites worked with HT and 5/8 wave\" articles, and want to figure out\nwhat the weak link in my station is.\n\n\nRX path:\n\nEggbeater II antenna mounted at 15 feet. This is built to the K5OE Eggbeater\nII spec (http://members.aol.com/k5oejerry/eggbeater2.htm) using RHCP but\nuses a 100 ohm phasing line using two 50 ohm coax lines done in parallel,\nused in a balanced configuration, instead of 93 ohm RG-62. Antenna was\n'redesigned' in MMANA-GAL to match exactly 100 ohms and to use 6mm diameter\ncopper tubing instead of AWG 12 house wire. It is peaked for SWR < 1.1 at\n436 MHz, and is less than 1.5 at 435.0 and 437.0.\n\nOur lot is lightly treed, but there is no wood (natural or otherwise) within\nsix feet of this antenna. A good chunk of the sky, mainly northwesterly\nlooking, is partially obscured by a large tree, but right now the leaves are\noff and it shouldn't kill the signal that much...should it?\n\nThis antenna is the secondary antenna on this mast and is mounted on a 3\nfoot PVC stand-off pipe. The primary antenna is a Diamond F22A mounted at\napproximately 18 feet. It has a 10 foot vertical element and three 1/4 wave\nhorizontal radials. It is not used in the satellite station but I wanted to\ndescribe it, in case it is interfering (I suspect it is.)\n\nEggbeater is fed through29 feet of 213 spec coax (5.1 dB loss/500 MHZ)\nterminated in well done PL-259 connectors. I have verified this particular\ncable's loss at less than 2 dB at 432 MHz, using my Icom PCR-100's accurate\nS-meter and a known signal source.\n\nMy latest upgrade: RX chain goes into a homebrew bypass relay / Ramsey\npreamp box (the relay is DPDT and switches the preamp in or out of the RX\nsignal path). The preamp provides approximately 18 dB of gain when inserted\nand using a test signal around 432 MHz. It has proven somewhat beneficial,\ngiving me 2-3 S-units advantage at certain points from the LO-19 CW beacon\n(Which I recently received at up to S9 with the preamp on a ~60 degree pass,\na new record so far).\n\nI have tested both with the antenna coax plugged directly in, and through\nthe relay/switch box, which is connected to the radios through a 3 foot RG-8\npatch cable. The preamp box uses runs of RG-174, but all runs are properly\ndone and less than 2 inches. Telay box and the patch cable has been measured\nto have 1-2 dB of loss when bypassed at 432 MHz. I know this can be\nimproved,but given my tests, I don't believe the plastic case of my preamp\nis killing incoming signals or anything (I switch coax lines quickly and it\ndoesn't kill weak but audible signals at all).\n\n\nReceivers:\nIC-208H dual band radio, rated at <0.18 uV for 12dB SINAD\nOR\nPCR-100 computer controlled receiver, rated at <0.34 uV for 12dB SINAD\n\nThe TX setup is currently an IC-271 pushing from about 4 to 38 verified FM\nwatts into a simple RHCP turnstile, recently built. It is mounted on a\nslightly shorter PVC mast about 10 feet away from the \"big mast\". It is the\nonly antenna on this pole, and is fed through 27 feet of 213 spec coax.\nPeaked at 145.8 MHz with SWR less than 1.1 . I know the turnstile pattern\nhas most gain directly overhead and has some shortages towards the horizon,\nbut I have plenty of theoretical EIRP to get on the LEO sats, I believe, and\nI'm not worried about the TX path right now.\n\nI'm just not getting the signal strength and intelligibility that I expect\nfrom this setup. For example, there was a theoretically perfect SO-50\nascending pass today at about 5:15 PM Central, 15 minutes plus duration and\nit peaked at almost 80 degrees elevation. I received the signal faintly\nstarting at 2 degrees, and it steadily improved to a 'fluttering S3\" at\nabout 8-10 degrees. I attempted to come back to a station that finished a\nQSO, because I thought it cleared - turns out,the signal DIED. I could just\nbarely track it for the rest of the pass, even when it was almost directly\noverhead at less than 900 miles altitude. Gave up when it was five minutes\nbefore LOS, with no contact made.\n\nSo, given my station description, what am I facing? Is my Eggbeater's\n'overhead 10dB null' design killing it? I would think that, as designed, the\ngreatly decreased path loss as the bird comes overhead should compensate for\nthis shortage, and then some.\n\nAs mentioned earlier, I'm also concerned that the Diamond F22's radials are\ndestroying the radiation pattern of this antenna. I'm in a rent house and\nhave to conserve masts as much as possible, but if it's killing me, I can\nmove the satellite antennas to a ~12 foot PVC mast instead of trying to\npiggyback them on my metal vertical mast.I've copied beacons and various\ncarriers from birds as low as 0.5 degrees, so I know the antenna 'gets out'\nokay at lower elevations. It's the high elevation periods that are\ndisappointing me.\n\nHow does my IC-208H compare to more refined receivers? Is it too deaf? I've\nconsidered feeding my IC-735 HF radio with a 435 MHz receive converter. This\nwould allow all mode 70cm reception with a very good radio (comments on the\nHamtronics converter boxes would be great). I'd love any comments on the\nHamtronics receive converters from those who have tried them out.\n\nI'd appreciate any comments and advice from the great minds on this list.\nThanks for taking the time to read up and give any advice or comments.\n\n73,\nMatt\n", "attachments": [] }