2 years ago, I converted a DX100 from 1625s to using EL34s, with good success. I also tested 6146s and found that they required a lower screen voltage, which made my job harder, and were also too fat for good cooling in that space. Not to mention the wide sockets. You can read my reports here - written over a period of weeks:
http://amfone.net/Amforum/index.php?topic=3789.0IMHO, the EL34s were perfect for the Apache-sized transmitter with a pair of 6146, and DX100 of course.
