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