Excellent classic pentode, Ken-Rad is the most common 307A type. Great KENRAD tube for SE amplifiers! I personally used it in few amps, here is small 307A VT-225 baby amp, it is also used in RH307A amp by Alex Kitic and Pete Milett’s 307A Push Pull Amp (great article about VT-225 307A)!!!.
Mostly dark coated, but some are clear glass.
In JAN boxes, longer life than National Union.
Before selection … All tubes are carefully tested on Neuberger RP370 for plate current and on Dynamic Mutual Conductance Tube Tester I-177-B for conductance.