Sometime between 1815 and 1945Z today, AO-51's IHU crashed. This happened after a few days of intermittent and unpredictable operation. Mark N8MH and I reset the satellite and started the repeater back up around ~2030Z, and lowered the output power to about 300 milliwatts. Battery voltage was low, around 4.9v, with cell 1 less than 1 volt. This is very troublesome, as the impending third cell failure will likely end our continuing operations, particularly if it fails shorted as the others have. We've also observed the transmitters cutting off around 4.7 to 4.6 volts prior to the last reset, in eclipse.
We'll do what we can, but her days are short. Let me ask once again for more reports, especially from the US operators, to the oscar.dcarr.org webpage. The command stations monitor this for changes in the operation of AO-51, and while worldwide participation is good, few US operators post to it.
Please support the several satellite programs worldwide, such as AMSAT-Fox, AMSAT-UK FunCube and UKCube, AMSAT-ZL Kiwisat, AMSAT-DL P3E, and others.
73, Drew KO4MA AMSAT-NA VP Operations
Next pass the repeater was still on but that the very low power levels we saw earlier. I crashed the IHU and attempted to restart, but ran out of elevation. More after tomorrow's afternoon passes.
Just as an FYI, and to answer some emails sent privately to me, AMSAT-Fox is designed to continue in "zombie" mode despite a battery or IHU failure, while maintaining control to FCC standards. See page 4 of http://www.amsat.org/amsat-new/fox/Fox1Systems.ppt
73, Drew KO4MA
On 11/25/2011 4:25 PM, Andrew Glasbrenner wrote:
Sometime between 1815 and 1945Z today, AO-51's IHU crashed. This happened after a few days of intermittent and unpredictable operation. Mark N8MH and I reset the satellite and started the repeater back up around ~2030Z, and lowered the output power to about 300 milliwatts. Battery voltage was low, around 4.9v, with cell 1 less than 1 volt. This is very troublesome, as the impending third cell failure will likely end our continuing operations, particularly if it fails shorted as the others have. We've also observed the transmitters cutting off around 4.7 to 4.6 volts prior to the last reset, in eclipse.
We'll do what we can, but her days are short. Let me ask once again for more reports, especially from the US operators, to the oscar.dcarr.org webpage. The command stations monitor this for changes in the operation of AO-51, and while worldwide participation is good, few US operators post to it.
Please support the several satellite programs worldwide, such as AMSAT-Fox, AMSAT-UK FunCube and UKCube, AMSAT-ZL Kiwisat, AMSAT-DL P3E, and others.
73, Drew KO4MA AMSAT-NA VP Operations _______________________________________________ Sent via AMSAT-BB@amsat.org. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
Yesterday afternoon (T-Day) there was a good high elevation pass over DM04 around 2300 UTC. AO-51 was extremely weak but I was still able to make out some voice just above the noise floor using my TH-F6a and SRH-320a whip antenna. When the conversation ended I gave my callsign followed by my grid square and just before the sat dropped below the horizon I was able to make out a male with a subtle accent calling me back. It almost sounded like K6VUG whom I talked to just an hour before on AO-27, but I cant be sure. Anyways, shes weak but hangin in there and certainly a tough bird. Hopefully she will be around a while longer.
On 11/25/2011 14:39, Andrew Glasbrenner wrote:
Next pass the repeater was still on but that the very low power levels we saw earlier. I crashed the IHU and attempted to restart, but ran out of elevation. More after tomorrow's afternoon passes.
Just as an FYI, and to answer some emails sent privately to me, AMSAT-Fox is designed to continue in "zombie" mode despite a battery or IHU failure, while maintaining control to FCC standards. See page 4 of http://www.amsat.org/amsat-new/fox/Fox1Systems.ppt
73, Drew KO4MA
participants (2)
-
Andrew Glasbrenner -
Bryan Herbert