I noticed that JJ is producing an EL509 power tube. Except that it is an octal version without the plate cap. The original EL509 was a horizontal deflection tube for TVs with a 9 pin base and plate cap. It seems like JJ shouldn't really be calling it an EL509, but I like that it is swappable with other octal power tubes (like KT-88 or 6550) as long as the PT can handle the extra filament current.
I have read where the KT90 was really a modified EL509 that was beefed up and put into an octal base. I wonder if this tube is JJs version of the KT90. Yellow_Light_Colorz_PDT_25 Could be fun to get a quad and play around but I don't see anyone selling them yet.
JT