This is an older, but informational, article on how to convert an armband radio into a ghost communication tool... Instructions on How to Make a Radio Shack 12-820 Ghost Box
This recommended 12-820 ghost box hack was originally discovered by Steve Hultay of Keyport Paranormal and has been dubbed the "Hultay Hack #2." The problem with some other infamous ghost box hacks are as follows:
12-470 - older radio that has become difficult to find, but the best ghost box if you can find one to buy and convert.
12-469 - older model radio that is easy to hack, but makes an obnoxious click if the white version of it. It requires an amplified speaker to work it.
20-125 - This is a good box but is more difficult to hack. Steve Hultay discovered this one, too.
Find a 12-820 Radio Shack Radio
Purchase a Radio Shack 12-820 arm band radio (if you can find one - production has since been discontinued) and remove the four screws on the back. Lifting the back cover off carefully, you will see two bundles of wires.
Both bundles should contain mainly gray wires; but with one red wire to the far right of each bundle. You are concerned with only the left bundle of wires. You will need to carefully snip the third gray wire from the left of the red wire of this first bundle (do this at your own risk - see wires illustration).
If you are able to remove one more screw from the circuit board, you can separate the circuit boards and confirm that this gray wire is the mute wire. It will cause your arm band radio to sweep without stopping when the up or down arrows are held down for about a second. Your radio should still work, and you can manually tune to any station; but now it should scan the FM or AM band without stopping. In our testing, we have noticed that, occasionally, the sweeping of the band will stop for no apparent reason, but overall the hacked radio worked quite well for us.