First, for a cleaner connection, you should be able to use one of these plugged into the back to the tv to give you the "F" type connector you would need to attach a digital converter box...
http://www.radioshack.com/product/index.jsp?productId=2103466
Then, for the converter box, you could go with one of these...
http://reviews.cnet.com/tv-hdtv-tuners-receivers/winegard-rcdt09a/4505-6487_7-33280760.html
Unfortunately, it doesn't look like the converter is sold in stores any more, but I did find a used one for sale on Amazon...
http://www.amazon.com/Winegard-RCDT09A-Digital-Analog-Converter/dp/B001DFVJ9M/ref=cm_cr_pr_product_top
It's got mixed reviews, but I don't know that there are any alternatives for a portable converter box out there now. Also, as noted in the Cnet review, the battery pack is sold separately, so you would have to track that down as well. You might be able to find a different battery pack with the same connector type and same power/amp ratings if you can't find this particular model.
Would make for a nice conversation piece.
On the other hand, if you are looking for something to go in your bomb shelter, I would suggest a wired converter box with better reception and a generator.
First, for a cleaner connection, you should be able to use one of these plugged into the back to the tv to give you the "F" type connector you would need to attach a digital converter box...
http://www.radioshack.com/product/index.jsp?productId=2103466
Then, for the converter box, you could go with one of these...
http://reviews.cnet.com/tv-hdtv-tuners-receivers/winegard-rcdt09a/4505-6487_7-33280760.html
Unfortunately, it doesn't look like the converter is sold in stores any more, but I did find a used one for sale on Amazon...
http://www.amazon.com/Winegard-RCDT09A-Digital-Analog-Converter/dp/B001DFVJ9M/ref=cm_cr_pr_product_top
It's got mixed reviews, but I don't know that there are any alternatives for a portable converter box out there now. Also, as noted in the Cnet review, the battery pack is sold separately, so you would have to track that down as well. You might be able to find a different battery pack with the same connector type and same power/amp ratings if you can't find this particular model.
Would make for a nice conversation piece.
On the other hand, if you are looking for something to go in your bomb shelter, I would suggest a wired converter box with better reception and a generator.