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{
    "url": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/I27RSWCBHQUFADJNASX4MXWX3VVMOK2M/",
    "mailinglist": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/",
    "message_id": "[email protected]",
    "message_id_hash": "I27RSWCBHQUFADJNASX4MXWX3VVMOK2M",
    "thread": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/thread/I27RSWCBHQUFADJNASX4MXWX3VVMOK2M/",
    "sender": {
        "address": "w9gb (a) icloud.com",
        "mailman_id": "b156075684ac4750b888b2dd14137a40",
        "emails": "https://mailman.amsat.org/hyperkitty/api/sender/b156075684ac4750b888b2dd14137a40/emails/"
    },
    "sender_name": "Gregory Beat",
    "subject": "Re: [amsat-bb] Mast mounted low noise amps",
    "date": "2018-01-20T22:28:19Z",
    "parent": null,
    "children": [
        "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/PIMM2JCG47XISPWLK4H7IVM3WJFQPYJU/"
    ],
    "votes": {
        "likes": 0,
        "dislikes": 0,
        "status": "neutral"
    },
    "content": "Bill -\n\nThe Icom AG-series of mast mounted pre-amplifiers for weak-signal and satellite work are now legacy (I believe Icom has discontinued recently).  A lower noise figure of the active device (FET, MMIC) is important for satellite work (sky), than weak-signal work (noisy terrain/earth).\nHigh noise-levels with the AG-series are often attributed to a Failed FET or an improper FET replacement by an earlier owner.\n\nNewer FETs have ESD / static protection, while older designs — DID NOT !\nNearby lightning strikes can damaged the FET on the AG-series pre-amps.\n\nCentral States VHF Society annually performed Noise Figure tests on a variety of devices.\nThis may be useful, as you examine modern devices or recent surplus.\nhttps://csvhfs.org/index.php/vhf-101/24-csvhfs-history/noise-figure-results\n\nThe Icom mast-mounted pre-amplifiers (AG-25, AG-35) used the dual-gate Toshiba 3SK121 Dual Gare FET (discontinued).  Schematics and manuals for the Icom AG-series are available via the Internet.\nhttp://www.radiomanual.info/schemi/ACC_preampl/Icom_AG-35_user_IW2HEU.pdf\nMODS.DK has the parts list and hand-drawn schematic for AG-35 (1999),\nthe othe file AG-25 etc. Instructions has schematic for AG-25 (last page).\n\nToshiba 3SK211 — GaAs MES FET, Dual-Gate, UHF, 10V, Idss>20mA, Up<4V\nhttp://pdf.datasheetcatalog.com/datasheets/134/499109_DS.pdf\n\nIcom AG-series (brochure)\nhttps://www.icom.co.jp/world/support/download/manual/disp_down.php?SWT=&ID=20010101248&GNR=Options&TYPE=I&PDNM=IC-AG1/IC-AG25/IC-AG30/IC-AG35/IC-AG1200&INQWORDSWT=No&INQWORD=\n\nIn 2012 and 2013, Earl Andrews, VE3AB (Netty Electronics) \nhttp://www.nettyelectronics.com/\ndid comparison testing of various Dual Gate FETs, used by Icom, Yeasu, and Kenwood since the late 1970s.\nhttp://www.earlandrews.com/dgshootout.html\n\nEarl also noted Eastern Asian counterfeit products (various FETs), largely from China.\nThe Phillips/NXP BF981 being a common bad Chinese export (March 2014 & June 2015)\nhttp://www.earlandrews.com/dgmosbadagn1.html\n\nhttp://www.earlandrews.com/dgbadagn.html\n—\nRF Parts — Low Noise FETs\nhttps://www.rfparts.com/rftransistors/transistor-misc/transistor-misc-lownoise.html\n===\nAs far as a MMIC swap, I have not seen anything posted (YouTube, Icom boards, amsat-bb reflector), BUT that does not mean it has not be attempted or accomplished.\n—\nBeginning this month — Corey Abercrombie, N4NGZ, acquired the exclusive rights to manufacture, sell and repair the existing DownEast Microwave, Inc. (DEMI) VHF/UHF Transverter product line and all past VHF/UHF transverter products. \nhttps://www.downeastmicrowave.com/\nQ5 Signal, LLC\n17704 County Road 455\nMontverde, FL 34756\n\nSales:  [email protected]\n\nSupport:  [email protected]\n\n\nCorey may be a source for current production UHF/Microwave devices, now or in future.\n==\nJay Rusgrove, W1VD owner of Advanced Receiver Research (ARR) has a number of excellent Gallium Arsenide low-noise preamplifiers (LNA’s).\nThe ARR MSP144VDG-160 and MSP432VDG-160 models are often recommended for fixed satellite earth stations.\n\nHigh Performance, 160 Watt Mast Mounted, Amateur Radio Preamplifiers\nhttp://www.advancedreceiver.com/page10.html\n\nGreg, w9gb\n== \nFrom: Bill Acito <[email protected]>\n\nWhat's the opinion/consensus of the older ICOM AG series, as an \neconomical alternative? Can they be updated, with say, a different MMIC?\n\nBill W1PA",
    "attachments": []
}