Trudy's Radio Repair

 is an unmarked quest in Fallout: New Vegas.

Quick walkthrough
In order to fix Trudy's radio, located behind the counter of the Prospector Saloon, simply activate it as if you were going to turn it on and it will bring up a menu to either leave it alone, or repair it. If you have a repair skill of at least 20, you can fix it. Report back to Trudy for some caps.

Detailed walkthrough
To fix the radio, you need a repair skill of at least 20. (A Fixin' Things skill magazine can be used to raise your repair skill, if needed.) Trudy mentions her broken radio when you talk to her, and you can offer to fix it in dialog, but this is not necessary. All you have to do is walk behind the counter in the Prospector Saloon and activate the radio - once you do, a message box will pop up with two options: "Repair the Radio" or "Leave it alone." If you're able to repair it, report back to Trudy. She rewards you with 50 caps, or 75 if you pass a Barter challenge (skill of 20 required). You'll also receive 10 XP for fixing the radio and 25 XP if you can pass the Barter challenge.