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{
    "url": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/W5KWJE4F5BXC6JA57MNVKLUQKNAMUYM7/",
    "mailinglist": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/",
    "message_id": "[email protected]",
    "message_id_hash": "W5KWJE4F5BXC6JA57MNVKLUQKNAMUYM7",
    "thread": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/thread/FIXEHRDWV23VJBSVYM4N3U2S5UCOBTA4/",
    "sender": {
        "address": "al7eb (a) acsalaska.net",
        "mailman_id": null,
        "emails": null
    },
    "sender_name": "Edward R. Cole",
    "subject": "[amsat-bb] Re: ARR Preamp Documentation",
    "date": "2007-01-03T04:25:13Z",
    "parent": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/FIXEHRDWV23VJBSVYM4N3U2S5UCOBTA4/",
    "children": [],
    "votes": {
        "likes": 0,
        "dislikes": 0,
        "status": "neutral"
    },
    "content": "At 03:15 PM 1/2/2007 -0800, Mark Brueggemann K5LXP wrote:\n>\n>\n>Poked around the web for a while and didn't see any downloadable \n>data on ARR preamps.  I am trying to find out what the exact \n>DGFET/BPT/GaAsFET the 144 and 430 models use, and if the \n>DGFETs/BPT/GaAsFET's are interchangeable.  I anticipate blowing \n>them up when I get my sat setup going soon, and I would like to order \n>up some spare devices (exact replacements or suitable substitutes).  \n>I have the PxxxVDG's but I'm reading that the DGFET and bipolar \n>versions are less ESD fragile than the GaAs ones albiet less gain.  \n>Is there an advantage to one over the other in practical ham \n>satellite applications?\n>\n>Thanks, \n>\n>Mark K5LXP\n>Albuquerque, NM\n\nMark,\n\nI have had several P144VDG preamps and used mgf-1302 or 1402's for\nreplacement.  However, these devices are difficult to find nowadays (I\nscored several away for spares).  I have a P144VDA that is used as a second\npreamp after my mast mounted 2m-eme preamp.  I uses a 3SK48 MosFet.  It is\nused as a line amp so its 1 dBNF is sufficient.  The MosFet is less\nsusceptible to overdriving by the 1st preamp.  I bought a spare 3SK48\ndirectly from ARR after accidently transmitting into the preamp.\n\nAlthough the GasFet is static (ESD) sensitive, I have not had any problem\ndamaging them while replacing them in the preamp.\nThe issue of the Fets or BPT devices is they are higher noise figure\ndevices, not that they are less gain.  It is true the mgf-1302/1402 will\nproduce 22-25 dB gain at about 0.5 dBNF.\n\nThe devices are not interchageable, though.  Bias circuitry and operating\nvoltage vary by device.\n73's,\nEd - KL7UW \n=========================================\nBP40iq,  Nikiski, AK      http://www.qsl.net/al7eb\nAmsat #3212\nModes: V - U - L - S\nUSA Rep. for Dubus Magazine: [email protected]\n=========================================\n\n",
    "attachments": []
}