This is a multi-phase puzzle with a series of various tasks, including arcade elements.
METER C: There are multiple solutions. A simple way is to deduct (from the target value) one of the TUNE increments [ F (fine) = 30 or C (coarse) = 80 ] as many times as needed until you get a multiple of the other increment. Set TUNE accordingly and make the calculated steps, then switch to the other position and make the moves with that.
Argon 220 = 2x30 + 2x80
Xenon 280 = 4x30 + 2x80
Neon 200 = 4x30 + 1x80
Krypton 260 = 6x30 + 1x80
Helium 180 = 6x30
Jonathan will not bother with other gases listed in the instruction.
METER D (watch out for the sound too!)
Argon 110 (range 100-175)
Xenon 225 (ranges 150-350 or 180-300)
Neon 120 (range 100-175)
Krypton 320 (range 150-350)
Helium 195 (ranges 100-175, 150-350 or 125-200)
METER B is straightforward.
METER A: Watch out (or listen) to the right wave form and observe the movements of the METER A indicator. Click the START button while the appropriate wave form is shown AND the indicator is NOT in the red zone. (You have to wait for the right moment)
The detail shown on the piece of paper can only be found in Xenon. Click the bottom of the line (in the transparent grey area) which is in the same position as the red line on the paper. The number appearing in the Value field (to the right) is 529 (THz), this is the wavelength you need.
Use the Convert-R app on the phone to convert it to nanometers. Select Wavelength for tool type, Terahertz for Measurement 1 and nanometer to Measurement 2 (Scroll down to find them). Enter 529 as the quantity and press START. The result (the integers) is the code: 566
PHASE 4 is inactive, you don’t need it.