I'm always amazed by people who obliviously sell obviously bad items.

http://cgi.ebay.com/ANTIQUE-TELEVISION-TUBE-SYLVANIA-/350393024972?pt=Vintage_Electronics_R2&hash=item51950d41cc

Not afiliated

Some info on this thread:
http://www.videokarma.org/showthread.php?t=248795
It is possibly a radar display tube, in which case a center beam burn is pretty common.
jr