Can't help with the Bit-3 unit, but the power
supply for my 850
interface is P/N C014319, is marked for use with Atari 400/800 systems,
and is listed as 9.5 VAC output @ 1.7Amps. Hope this helps.
Thanks for the info! I just happen to have an extra one of these PSU's
sitting here. Isn't this the same PSU that powers the 800 itself?
Yup, it sure is. Sounds like you are in luck!