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AO-7 Predictability.

Between the 9th and 19th of January I've observed the mode change from A to 
B on AO-7 to be consistent and regular. This shows that the 24 hour timer is 
functioning as it was designed to do ... 31 years! ago.

I assume the reason for the present "predictable" mode changes to be the 
fact that the satellite is not, nor will be, in eclipse until at least 

After checking the log on "THE AO-7 RESOURCE PAGE" I estimated the 
switchover to be at
approximately 08:30 UTC daily. However, on the 17th of January, I noticed 
the changeover happened at precisely 08:57 ... in the middle of a Mode-B QSO 
with UA9CP ... so I immediately switched to mode-A and carried on the QSO 
... therby confirming the time of the mode change on that particular day.

Speculating ... this deviation could be due to the extra temperature seen by 
the satellite while not in eclipse. Those interesting in the orbital 
mechanics can plug the date and time into their favourite tracking program 
and "see" where the satellite was. The newly updated "AO-7 RESOURCE PAGE" 
now contains links to charts showing the current eclipse forcast.

The designers of this particular piece of hardware must be somewhat 
surprised that it's still functioning after 31 years in space, taking into 
account the radiation bashing it must have experienced in the last three 

Perhaps AO-7 is not yet finished with dishing out surprises.

The ESA and NASA take note!.

73 John.   <la2qaa@amsat.org>
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