Category: Ham Satellite news

Senaste nytt angende Oscar 40:

Initial attempts to turn on the K-tx with short machine code commands did not result in a detectable signal, but this will be repeated. Several additional cycles with the S2 have been repeated as well without result. These attempts always terminate with transmitter off commands, and simple commands to try to switch the battery to the aux. mode.

Our hypothesis remains that we have a battery failure clamping the voltage low. We re looking at the spacecraft physical and electrical layout and even the flaky heatpipe reading to see if we can come up with a more detailed failure point explanation.

If our theory is correct, the remaining cells of the main battery are taking quite a beating as the BCR s try unsuccessfully to bring them up to the set point voltage of about 28 volts. We expect that more than 6 amps are flowing through the remaining cells in the main battery and this
current will increase by about 30% as the solar angles improve. We only need for one of these cells to lose enough electrolyte to open and we could be back in business. I ll repeat my comment from before that time is
an unknown here and days or weeks without result do not mean ultimate failure.

I will be out of town for two days on an unavoidable business trip, but will update the bulletin board when I return on Sunday. The command team will continue to try to regain the S2 and K Tx s and report any successes here.

–W4SM for the AO-40 Command Team

Klla: W4SM

Oscar 40 har ftt ngot problem med batterierna s passbandet r avstngda just nu. Problemet undersks:
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On orbit 1486, the main battery voltage ran lower than expected. This was due in part to usage and high solar angle as mentioned previously, but even after the passbands were shut off automatically the voltages did not come
back up as expected, in spite of apparently positive battery charge currents. At the beginning of the eclipse on orbit 1486 at MA =225, the battery voltage rapidly dropped just below the S2 Tx cutoff voltage of 24.0
volts and the S2 Tx shut down. to protect the battery and IHU s. The eclipse ended at about MA=237, approx. 55 minutes later. We expect the S2 Tx to start back up as programmed at MA =2 (as I type this), though it has
been known to be balky before on restarts and could require manual cycling.

The command team is investigating this anomaly to determine if the main battery may have developed a single bad (shorted) cell or if there is a problem with the battery set voltage, solar array set voltages, or other
problem. Until we sort this out the passbands will be off for one or more orbits. If the battery charge or array set points are wrong, they can be changed. If we have one bad ( shorted ) cell we can reset charge/trigger points to account for this, and we have the completely redundant auxiliary battery, if needed. We hope to be able to work through this and correct things without too much down time.

We ll update you here as soon as we know more.

– –W4SM for the AO-40 Command Team

Klla: W4SM

Alon Alat 350/0 passbandet MA40-180

Mnga DX tillnskas!!

Klla: amsat