appears to be a ham or FM transmitter tube
The 813
beam power tube was very popular with amateur radio operators following WW II. The tube remained a staple of amateur radio until single sideband became a popular operating mode in the late 1950's and early 1960's.
appears to be a ham or FM transmitter tube again.
you prolly hadn't noticed, but this is a home audio forum , not a commercial FM transmitter forum. If that's what you have to dredge up to prove a point, then things seem rather sad. 2 million watts + ?? :rotfl:
seems answering home audio questions with "There are many to be had at well over 500 watts." then reference to non-home audio gear is really very bogus.