Fallout 3/Radio Signals

Only a small tip here.

You will encounter large radio towers, which after turning them on, transmit strange radio messages. This means that a shelter is nearby. Search the surroundings for an underground shelter. Usually these have a small collection of items. One has a bobblehead (near the Deathclaw cave). And another one also has a secret passage to a torture chamber. (If you enter this chamber the raiders who used it will return).