Caching in with Three Dog

 refers to an unmarked quest in Fallout 3.

This quest can be activated after you discover your father's whereabouts from someone other than Three Dog, or by using a successful Speech check to have him tell you where your father is. This is an alternate quest reward if you decide to complete the Galaxy News Radio quest anyway. After you finish the quest, Three Dog compliments your dedication and then gives you a note titled "The Weapons Cache", the key to the weapons cache and the map marker for Hamilton's Hideaway where the cache is located.

Although "The Weapons Cache" note says "Enclosed, you'll find the coordinates to the weapons cache... in Hamilton's Hideaway," there is no map to show you the actual location of the cache. In addition, since this is an unmarked quest, it is not possible to use "Show active quest notes" to find the precise location of the cache. The cache is behind a cell door in the northwestern-most area, behind some rubble.

Reward

 * Guns and Bullets
 * Mini Nuke
 * Stealth Boy
 * Combat Armor/Metal Armor/Power Armor
 * Combat Helmet/Metal Helmet/Power Armor Helmet
 * Power Fist (sometimes)
 * Assault Rifle
 * Frag Grenades