-on BrE AmE ɒn, ən AmE \ ɑːn, ən —When this is a true suffix (e ˈ lectron) , it is usually strong. When it is a mere ending ( ˈ common) it is usually weak, but there are a number of exceptions ( ˈ coupon) and words where speakers disagree ( ˈ lexicon) . In many cases British English prefers a weak vowel, American English a strong vowel ( ˈ Amazon).
-ON
Meaning of -ON in English
Longman Pronunciation English Dictionary. Английский словарь произношений Longman. 2012