Tachometer and Radio won't power up

[ih8vols]

Hey guys. I have a 79 C10 Silverado. Other than the few minor things I've done to it, it's all original. I've been doing some upgrades and fixing her up a bit.

I finally got the radio installed and it was working fine. A few weeks later, I started noticing the truck was running rich. I then decided to install a tachometer so I could adjust the carb. I decided to use the power running to the radio to power the tachometer. Now, neither the tach or the radio works.

I checked the fuse and it's fine. Any ideas? Should I find another source to power the tach? I'm very much a newbie with cars, so break it down in laymen terms.

Appreciate the help!

Here's the tach I put in: http://amzn.to/1rz9TXx

Here's my radio: http://amzn.to/1T5fd14