Portal/Transmission Received

The newest achievement, added in March 1, 2010, requires the player to find one (or more in some larger stages) radio(s) in each level and bring it to specific points. A radio will have a red light on the front if it hasn't been brought to the correct location. The music will change to static as you approach the correct location, and then to a hidden signal when you have arrived, at which point the light will turn green. The light persists across saved games.

The hidden signal that is picked up may be a Morse code signal, or sounds similar to those found on modems. To get full benefit out of them, you need to use sound recording software, or otherwise extract the audio files from the game.

Chamber	Radio initial location	Achievement location
Chamber 00	In the relaxation vault.	The button room, just over the button.
Chamber 01	On the camera to the right of the entrance. It can be grabbed before dropping down.	The exit, just before the door to the emancipation grid.
Chamber 02	On the wall containing the hole through which the portal gun fires. One way to reach this is to, while near the orange portal, shoot a blue portal at the ceiling just above the radio.	Where the portal gun was initially located.
Chamber 03	On the camera near the exit. Knock the camera and radio down by shooting the wall with a portal.	By the ceiling above the second pier and the wall facing the orange portal, at the corner.
Chamber 04	Released with the storage cube.	The entrance.
Chamber 05	Behind the door opened by two buttons. Shoot a portal under it before stepping through the door.	The pit previously containing a cube.
Chamber 06	Above the pellet launcher. Shoot a portal near the launcher and grab it through the portal.	The exit lift.
Chamber 07	Under the entrance platform, behind the stairs.	The exit.
Chamber 08	Below the moving platform's initial position.	Near the chamber number.
Chamber 09	Within the small opening between the two sections. Methods of retrieving are described in the walkthrough for this chamber.	The exit.
Chamber 10	In the third section, on a tiny ledge on the left. To get it, proceed with the test until you are on the other side of the gap, then stand as close as you can to the radio and jump towards it while pressing  E  repeatedly.	The orange portal.
Chamber 11	In front of the door between the main and final areas. To reach it, shoot a portal near the radio, and grab it by standing within the portal.	Where you collected the orange portal gun.
Chamber 12	On the middle support of the panels that are extended furthest. To reach it, place portals on the angled platform and the bottom, then fall through starting from the first level.	Directly under the angled panel.
Chamber 13	On the right-hand side of the main room. Grab it from the moving platform.	The window above the button of the initial room.
Chamber 14	Between the button and the door it powers, on the right wall. Use momentum and a portal below it to grab the radio.	The stationary platform in the middle of the sludge.
Chamber 15	Hidden up behind the extended panel you use to launch yourself through the field. Place a portal on the ceiling next to and behind the panel, and you can grab it.	The entrance.
	In the final room, within the pellet receiver container. Press the two buttons, and then place portals in a way that allows you to jump into the enclosed area (two portals on the ground, one being in front of the container). GLaDOS will release you from the area.	The exit.
Chamber 16	In the side room with multiple storage cubes.	In the secret area behind the extended panel, next to all the scribblings.
Chamber 17	Under the third lift leading to the exit.	The incinerator.
Chamber 18	In the Ratman Lair, found after the first fling.	The signal point can be reached by firing a portal on the ceiling above and slightly to the right (facing the 3-dot platform) of the "two Dot" symbol on the floor of the next platform, and holding the radio through a second portal on the floor. You will need to crouch to do so without dropping the radio.
	In the room with all the turrets on platforms. It is on top of the box which has the pellet receiver (behind a door).	Where the moving platform allows you to jump to (with a small button).
	After the door that is opened with the cube. It is at the bottom of the drop to the left of the door.	Just before the exit.
Chamber 19	In the giant incinerator, on the left. Set a portal just above it, and use it to escape the incinerator. Then create another portal, and go through half of it to catch the radio without being burned.	In an office, soon after the two big fans.
Escape 00	Just after the load screen, you will find some stairs to the right. Under the stairs the way is blocked, but portal through the fence and crawl into the vent to a small area containing supplies and the radio.	Above the next horizontal pistons you see, in the corner across from the red symbol.
Escape 01	After being ambushed by three turrets, you will find the radio near the broken sentry.	In the next room, after knocking down the turret, enter the alcove containing supplies.
Escape 02	When you enter the turret arena, the radio is in the lower section, on the opposite side of where you entered the arena.	When you exit and reach the two turrets that are dropped from the ceiling, Fling up to the next level and bring the radio near the green generators.