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{
    "url": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/QKFU5EXIJOE3DO4WN5XXV2WJ5C3M2SJN/",
    "mailinglist": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/",
    "message_id": "[email protected]",
    "message_id_hash": "QKFU5EXIJOE3DO4WN5XXV2WJ5C3M2SJN",
    "thread": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/thread/QKFU5EXIJOE3DO4WN5XXV2WJ5C3M2SJN/",
    "sender": {
        "address": "broberts (a) mta.ca",
        "mailman_id": null,
        "emails": null
    },
    "sender_name": "Bruce Robertson",
    "subject": "[amsat-bb] Re: Pre amp question",
    "date": "2006-12-13T10:56:23Z",
    "parent": null,
    "children": [],
    "votes": {
        "likes": 0,
        "dislikes": 0,
        "status": "neutral"
    },
    "content": "\n\nQuoting Steve Raas <[email protected]>:\n\n> As I prepare for getting on the birds.. I decided to test out this\n> AG-25\n\nSteve:\n\n(Once again, it has to be said that I'm new at this stuff, too, and I'd be\nhappy for the folks on this list who have taught me over the last two years\nto correct any errors.)\n\nWhat you describe in your letter would, I believe, correspond to the\nsituation in which the noise figure of your preamp is not much better than\nthe noise figure of the front end of your receiver and there is not very\nmuch loss between the preamp and the radio (i.e., not very long a run of\ncable). Is it possible that you hooked it up with a short run of cable in\nthe shack, shorter than you usually use for terrestrial work? Perhaps your\nreceiver nf has improved. If the preamp and the front end have the same\nnoise figure and there is significant loss in the cable, however, you will\nwin with this setup. \n\n>From my experience, if your cable is low loss, a 145 preamp isn't as\nnecessary as a 435 one because thermal noise is higher and the cable won't\nding you as much. My preamp went funny and it wasn't a complete tragedy. \nWho knows, maybe *my* 145 preamp is the pits, too :-) Those ICOM units are\na bit dodgy, though: they don't seem to specify their noise figures very well.\n\nI think all would agree that 435 MHz is the band that *really* needs a\npreamp. You want one that has a 1 dB noise figure or less for the usual 15\n+ dB of gain. Advanced Receiver Research and SSB USA are known to be fine.\nMy in-shack ARR preamp is *amazing*. (I have a short run of heliax between\nantennas and preamp.) Be sure to get one that switches on xmit.\n\nAs far as setting up a station, I'd try building something minimal to start\n so that you can observe the improvement each added element brings. Use a\nfemale-female N connector in place of a preamp on 145 at first and observe\nthe helpful always-on beacon on VO-52. How high above the horizon does it\nneed to be before you can hear it over the noise? before it starts to move\nthe S-meter? (Don't try this with AO-7; it's too weak.) Even on 435, you'll\nhear *something* without a preamp if you have an antenna with some\ndirectionality. (And, as I've mentioned in the previous letter, even a 1/4w\nvertical will bring in LO-19 and others.)\n\n73, Bruce VE9QRP\n",
    "attachments": []
}