The 2000 needs an external supply. I found my trusty old Astron RS-20 a bit
undersized at some times, like 160 cw contests, so I replaced it after a
year with a RS-35 and it hasn't broken a sweat in the past 5 years. The
smaller supply probably would have been fine, but I think the extra margin
was worth it.
73, Steve KW3A