On this page of our guide to Wolfenstein: Youngblood you will find a detailed description of the Transmitter side quest. This task is about finding and infiltrating an underground Nazi station. The goal is to locate the radio transmitter.
Who's commissioning the mission: Talk to Penda Niang in the catacombs.
Mission difficulty level: Do not proceed with this task if your sister is not at least level 22 of experience.
Use the subway network to move to Political Detention Area 4. Set the described mission to active and follow the instructions on the mini-map. The icons on the mini-map and the screen are quite confusing, as they will lead you to a closed building. Don't try to open the door, because it's not possible from the outside. Go left of the door and continue exploring the area until you find a path between buildings in the attached picture.
You will arrive near a building where the Nazis may reside (the same place was explored in a side quest called The Silent Outpost). But you don't have to fight them. The priority is to reach the descent to the canals marked by the game - it is shown in the picture above. You'll find the gate. The sisters have to lift it together and it will unlock the Detention Area 4 Sewer.
It is very dark in the sewers and as a result you have to help yourself with a flashlight. You can travel with a weak weapon in the other hand, or use Sturmgewehr weapon more often, which has a factory-installed flashlight.
Travelling with the flashlight off may make it easier for you to surprise enemies from the underground, but you may as well fight them traditionally. Unfortunately, there are not many light sources here and this will make it difficult for you to use certain types of weapons.
While exploring the sewers, you can also meet Supersoldats in addition to your regular opponents. Select the right weapon and watch out in the narrow corridors.
The destination is the room from the above image. Here you will find the Transmitter. Go back with it to the commissioner of the quest - to Pendy.
Rewards: 8600 XP, 430 silver coins, 1 skill point.