Svetlana in California converted my old NCL-2000 to their 4CX400's but it
was a major task. The RFC choke has hot spots on several bands and they had
to build a separate sub chassis for the tubes. I heard they also tried a
single 4CX800 in another NCL-2000.

There are two off shore copies of the 8122 beside the original RCA versions.
I had a pair of the off shore tubes in a Hallicrafters SR-2000 and they
seemed to work fine.

8122 and the off shore version are available right now some at reasonable
rates. The thing that needs changing is the relay and the RFC choke.
Svetlana had my old amp working on 80 to 10 including 17 and 12. I think
Svetlana closed USA ops and moved 100% overseas altho they do selll thru USA
companies.

Dave K4JRB