Base Exterior - Sending the S.O.S.

When Lara makes it to the panel, she contacts Alex using the walkie talkie. He explains what she needs to do. Following the on-screen prompts, first, swivel the left stick clockwise or press the Left direction key on the keyboard to tune the radio.

When the needle on the readout on the right points to the fourth tick mark from the left, you should hear an announcer's voice saying you're tuned to the International Emergency Response System. Press Interact to make Lara move her hand to the left dial.

Now swivel the left stick clockwise or press the Left direction key on the keyboard to "Adjust Squelch" (whatever the heck that means).

I'm not sure if there's a particular sweet spot on the left dial, but after a bit of rotating, the on-screen message changes to "Hold The Signal."

Then you just need to wait until prompted and press Interact to broadcast the S.O.S. Message.