production code AAA D0 Δ 7B3 & AAA D0 Δ 7C3
no stains on glass
same inner structure
copper rods
double full disc getter with studs
tested on Funke w19 tube tester
Test results 40mA (reference good at 26mA) same emission test results for both tubes
EL509 = 6KG6 = 6KG6A
Socket Magnoval (9-Pins), B9D Top contact with a cap.
Filament Heater Vf 6.3 Volt / If 2 Ampere / Indirect
box 153