The 6SA7 has five grids: Grid 1 (oscillator), Grids 2 and 4 (screen, connected together), Grid 3 (signal input), and Grid 5 (suppressor, connected to cathode at socket).
Maximum ratings: Va=300V, Vg2/g4=300V (supply), Pa=1W, Pg2/g4=1W, Ik=14mA.
Conversion transconductance at Eg3=-2V: 450 umhos. Oscillator transconductance (grids 2 and 4 to plate): 4500 umhos.
Self-excited operation uses 20kΩ cathode resistor. Separate excitation also supported.