From Balatonkenese follow the way to Papkeszi, and after the end of the village you will find the tower at the left side of the road.
The cache is hidden in the pipe of the tower's sipre. This is the closest vertical pipe to the ladder. You can take out the 35mm film cansister by pushing it in (!), because it's fitted by a rubber which doesn't move upwards, so if you push the plastic box up, they both fall out.
There's always strong wind up there so think about to get dressed.