At that time 828, adjacent to 819, was assigned to Holland in Geneva75.

It was not used at that time, and AM channels Holland got in the 1975 conference were kept secretive.

Even when sollicitors got unused FM channels free for commercial use (Sky Radio) they forgot about the unused AM's.
Only late 90's these were allocated to commercial stations with 675 as a good example with Radio 10 (Gold). 828 was alo used by Veronica Hitradio and Arrow.