Ok. Let’s try this again…RCA 9TC240 Alignment

[Penthode]

The reason for detuning is so that you can clearly see the primary peak. Then you proceed to the discriminator zero adjustment. The "null" does not mean minimum. It means zero. The adjustment will swing plus and minus. You want zero. I normally set the vtvm to read zero mid scale so when I adjust the secondary adjustment I can clearly see it swing positive and negative.

Once the discriminator zero adjustment is made, you generally go back to the primary to slightly touch it up to make the discriminator peaks equal amplitude. Then again confirm the discriminator zero adjustment.