The front panel view shows the Simpson 1.5 Amp Plate and 500 milliAmp Grid current meters. The turns counter is an E. F. Johnson model 116-208 with 3 digits and a vernier dial for precise inductance tuning. The 4 switches are "Fan On", "Filament On", "DC On" and "Amp In". They are wired in sequence, 1st switch through 4th, and can only be switched on in that order. See schematic for details.