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{
    "url": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/2TKAJYATVQZB7XCWBFCVLFUF2TD5C4QR/",
    "mailinglist": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/",
    "message_id": "[email protected]",
    "message_id_hash": "2TKAJYATVQZB7XCWBFCVLFUF2TD5C4QR",
    "thread": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/thread/UUQ3IDXHDJEE3ZDQ6XPUPKE3BZAMMFCP/",
    "sender": {
        "address": "n4hy (a) idaccr.org",
        "mailman_id": null,
        "emails": null
    },
    "sender_name": "Bob McGwier",
    "subject": "[amsat-bb] Re: AO-07 Healthy CW]",
    "date": "2006-11-29T16:08:38Z",
    "parent": "https://mailman.amsat.org/hyperkitty/api/list/[email protected]/email/UUQ3IDXHDJEE3ZDQ6XPUPKE3BZAMMFCP/",
    "children": [],
    "votes": {
        "likes": 0,
        "dislikes": 0,
        "status": "neutral"
    },
    "content": "Tom Clark, K3IO wrote:\n> W9GB noted\n>\n>   \n>> I can identify the lab equipment on the bench (looks like my high\n>> school & college labs - 1970s) with the NiCad battery pak, EXCEPT for\n>> the rectangular box with metal handles to the right of the NiCads. \n>>  \n>> NiCad battery charger?   Homwbrew power supply?\n>>     \n> Greg -- the high-priced hardware (HP+Tek) show NASA Goddard property\n> labels. The cheaper power supplies in the back are Heathkits with AMSAT\n> stickers.\n>\n> The box you are asking about has a yellow Goddard tag. I'm trying to\n> recognize it, and to the best of my recollection it is a Coulomb-meter\n> that measured (on the mechanical counter you see on its panel) the\n> integrated charge/discharge current. Also my fuzzy memory tells me that\n> the heatsink device on clip leads was a prototype BCR.\n>   \nThere is nothing wrong with your memory!   Notice that it is in series \nwith the batteries,   it has a large transistor being heat sunk and I \ncan make out two high wattage resistors and an electrolytic \ncapacitor.    I think you are right.\n\n> Sil asked:\n>   \n>> I guess there's a special \"satellite design\" reason that double wires\n>> are used (instead of one thicker one) for the current carrying battery\n>> leads?\n>>     \n> The twin wires go to a pair of pins on the DA-9 connector, with two pins\n> providing greater current handling ability and redundancy. It also\n> appears that the V/2 telemetry tap has a pair of whit wires even though\n> it provided zero current. BTW -- the V/2 telemetry would be on 3B.\n>   \n>> Leaving aside Geoff's (vk2tfg) point that the telemetry may be\n>> irrelevant because of the doggy value in channel 6D, it would seem that\n>> the five top cells (between half volt point and +12V - numbers 2,3,4,5,6\n>> counting clockwise) are being charged with a current of 80mA and have\n>> reached a terminal voltage of 6.4 volts (8.8 - 2.4). This represents a\n>> voltage of 1.28 per cell (6.4/5) and is thoroughly reasonable. This idea\n>> is supported by the temperature of cell number 5 at 60.28 C. \n>>     \n>\n> The top 5 cells are fed by the black wire and are the LOW voltage side.\n> The 5 \"high side\" batteries terminate in the orange wire on the bottom,\n> The thermistor on cell #5 is on the low voltage side.\n>\n> The thermal design of the s/c ended up with internal temps ~20°-30°C\n> range (i.e. TLM values in the 40-50 range). I find it hard to believe\n> that a valid interior temperature would ever be in the 60°C range.\n>\n> Regarding all the telemetry speculation -- AFAIK, there is no indication\n> that the A/D converter is showing ANY valid data at all -- see also\n> Jan's comments at http://www.amsat.org/amsat/sats/n7hpr/ao7_tlm.html.\n>\n> FYI -- the TLM and its associate Morse encoder system was built with\n> discrete CMOS logic by John Goode, W5CAY in Texas. Memory fails me, but\n> I believe that the TLM/Morse board is on the \"back wall\" in the\n> photograph at http://www.amsat.org/amsat/sats/ao7/slideset/slide09.html\n> even thought the photo only identifies the module as the command\n> encoder. All the white IC's a early RCA ceramic 4000-series parts.\n> AFAIK, Oscar-6 & -7 were the first CMOS users in space. AO-7, with much\n> of this logic still functioning after 32 years and 2 weeks, certainly\n> holds the longevity record!\n>   \nJan told me that no reasonable data was found during the times Mike \nSeguin and I were attempting to command the spacecraft on the two \npossible command channels.     That was the last time I really looked at \nthis data in detail.  I wrote a python program to decode it all and it \nwas all crap.\n\n\n\n> [In case you forgot, Nov.15th was AO=7's 32nd birthday -- my favorite\n> picture of the launch is the \"7-UP\" contrail left by the Delta booster\n> http://www.amsat.org/amsat/sats/ao7/slideset/slide18.html]\n>\n> 73, Tom\n>\n>\n>   \n\nNice job on the memory for an OF like you!  (what are friends for after \nall).\n\nBob\n\n\n-- \nRobert W. McGwier, Ph.D.\nCenter for Communications Research\n805 Bunn Drive\nPrinceton, NJ 08540\n(609)-924-4600\n(sig required by employer)\n\n\n",
    "attachments": []
}