Down here in Australia at times we have experienced it were AO-7 would change modes mid pass during a non eclipse period. This was not due to to many stations but just the 24 hour time kicking in. You could follow the 24 hour period on http://oscar.dcarr.org.

We use to take betts on who would be the last one to speak before the mode change.

73s Malcolm - VK2MAL www.easy-sats.com