Audio "buzz" on a 1948 Motorola VK-101

[bandersen]

It means the sound has it's own IF stages that have to be precisely aligned to the video IF stages. Otherwise, you don't get the best picture and sound at the same point in the fine tuning.

With intermodulation the sound and video share the same IF with the sound being picked off after the video detector. Best video and sound tuning are always in sync.