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{ "url": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/NDRZVGBOY7F6XMYFFT4GGICTES2YF4XY/?format=api", "mailinglist": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/?format=api", "message_id": "[email protected]", "message_id_hash": "NDRZVGBOY7F6XMYFFT4GGICTES2YF4XY", "thread": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/thread/IIDM2QB42ZR36XPYEA5CHYFFM3YIM4HY/?format=api", "sender": { "address": "almetco (a) comcast.net", "mailman_id": "c7a5eb4d66ce4a1c96e6528422335a8a", "emails": "https://mailman.amsat.org/hyperkitty/api/sender/c7a5eb4d66ce4a1c96e6528422335a8a/emails/?format=api" }, "sender_name": "Greg", "subject": "Re: [amsat-bb] Mount Carmel HS ARC marine buoy deployed and transmitting", "date": "2020-07-16T23:24:51Z", "parent": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/TO7YUCCKBWTLTMNSYUYUG3WH2D2B3MCY/?format=api", "children": [ "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/NRCFB6G6ZPO6RLDKD4UR2N6XPGXFECNC/?format=api" ], "votes": { "likes": 0, "dislikes": 0, "status": "neutral" }, "content": "Great idea and thanks for sharing the technical details.\n\nGreg\nN3MVF\n\nOn Jul 16, 2020, at 7:20 PM, GEO Badger via AMSAT-BB <[email protected]> wrote:\n\nVery cool Phil.. Thanks for sharing that.\nAs an ex-employee of MBARI, I can tell you that we threw a lot of stuff in the water that took more development time and cost than yours with similar results.\n--- \nCiao baby, catch you on the flip side \n73 de W3AB/GEO \n\nhttp://www.w3ab.org\n\nYou can say \"over\", you can say \"out\", you just can't say \"over and out\". \n\n On Thursday, July 16, 2020, 03:48:27 PM PDT, Phil Karn via AMSAT-BB <[email protected]> wrote: \n\nOver the past year, Randy, KQ6RS and I have mentored the MCHSARC in\ndesigning and constructing a simple marine buoy that was deployed from\nthe R/V Sally Ride this morning about 700 km off the coast of southern\nCalifornia. It is up and transmitting WSPR on 20m using the callsign\nKQ6RS, and is being received all over the US and into Canada and Brazil.\n\nThe electronics is the 20m WSPR version of the WB8ELK \"pico tracker\"\nthat has been flown quite a few times (including by us) on long duration\nballoons. We removed the solar panels and substituted 21 ordinary\nalkaline D-cells wired to supply 4.5V. We estimate battery lifetime will\nbe 6 months.\n\nThe basic design was inspired by Bob, WB4APR, at the US Naval Academy.\nPhysically, the buoy is just a 5' section of 4\" PVC pipe, ballasted at\none end to float vertically in the water. The top is closed by a sewer\npressure test plug I found at Home Depot; it has a bolt in the center\nthat acts as a convenient feed-through and mounting point for the\nantenna, a stainless steel CB whip with a matching network designed,\ntested and carefully tuned by Randy. We use the sea as a counterpoise,\nbut to avoid direct metal/seawater contact we lined the inside of the\npipe with copper tape to form a capacitive connection. We probably spent\ntoo much time on this; Randy even modeled the electrical fields in the\nseawater with a professional RF analysis package.\n\nIn our first flotation tests in Randy's swimming pool we found that the\nballasted pipe, by itself, was remarkably stable in pitch, roll, sway\nand surge but oscillated a lot in heave (up and down). To damp this\nRandy added cross arms at the water line to add drag in the vertical\ndirection. (It wasn't our intent to mimic a religious icon but that's\nwhere the physics went.) Tuning the antenna required sea water, so Randy\ndid it from a dock on Mission Bay here in San Diego.\n\nWe tried to make this thing as rugged as we could. (My favorite saying\nto the students was that the sea *always* wins in the end, but we can\ndelay that long enough to be useful.) Everything inside is held in place\nwith epoxy or polyurethane foam. Randy reinforced the sewer plug with a\nPVC end cap with a hole cut in the center. Although the antenna is\nstainless steel, Randy covered it with a type of heatshrink with a\nwaterproofing compound inside. Activation was by removing an external\nmagnet placed over a parallel pair of normally closed magnetic reed\nswitches. (Using two instead of one was my idea.) We even argued how to\nguard against the crew forgetting to remove the magnet before\ndeployment. Randy found some adhesive that would dissolve and let the\nmagnet fall away; I suggested a big REMOVE BEFORE FLIGHT tag and a float\nthat would pull it away if it was tossed into the water.\n\nThat left the problem of deployment. We couldn't just drop it close to\nthe coast because it would quickly wash back up on the beach. We needed\na boat ride. We were originally going on a NOAA vessel in April, but\nthat trip was cancelled due to the pandemic. Randy secured a trip on the\nR/V Sally Ride, a research ship operated by Scripps Institute of\nOceanography and home ported here in San Diego.\n\nThis map shows the \"lawn mowing\" pattern they follow to measure and\nsample sea water off southern California. We were deployed early this\nmorning at the most southwestern point shown here:\n\nhttps://calcofi.org/cruises/2020-cruises/calcofi-2007sr.html\n\nFirst report was at 12:52:30 UTC this morning from 29 51.25N, 123\n37.50W. That's grid square CL89eu, which I figure is pretty rare for\ngrid hunters. The current carried us east into CL89fu at 20:32:30. This\nis a little surprising since we thought the currents in that area are to\nthe southwest. But that's why you do science!\n\nYou can track us on aprs.fi here:\n\nhttps://aprs.fi/#!call=a%2FKQ6RS-1&others=1&timerange=604800&tail=3600\n\nWe also show up on wsprnet.org\n\nhttp://wsprnet.org/drupal/wsprnet/map\n\nBecause of the funky way Bill encodes position in WSPR (which was never\ndesigned for this), you'll see some weird-looking callsigns (like\n0W7NFU) in addition to KQ6RS.\n\nThis was our first buoy, just to get our feet wet (ha ha). Now to think\nabout what we want to put in our *second* buoy. Two-way links, satellite\ntracking, sensors, the works. But remember the \"second system\" effect...\n\n73, Phil\n\n\n\n\n_______________________________________________\nSent via [email protected]. AMSAT-NA makes this open forum available\nto all interested persons worldwide without requiring membership. Opinions expressed\nare solely those of the author, and do not reflect the official views of AMSAT-NA.\nNot an AMSAT-NA member? Join now to support the amateur satellite program!\nSubscription settings: https://www.amsat.org/mailman/listinfo/amsat-bb\n\n_______________________________________________\nSent via [email protected]. AMSAT-NA makes this open forum available\nto all interested persons worldwide without requiring membership. Opinions expressed\nare solely those of the author, and do not reflect the official views of AMSAT-NA.\nNot an AMSAT-NA member? Join now to support the amateur satellite program!\nSubscription settings: https://www.amsat.org/mailman/listinfo/amsat-bb\n\n", "attachments": [] }