I just checked through my old radio club newsletters. A member of the club also found an expermintal 15GP22 at an old suburban Philadelphia repair shop. I checked but the serial number is different so he wasn't the seller.

About 15 years ago I use to go to a parts distributor in Trenton, NJ. I would stop by every few weeks for caps and such. While talking to the counter man he mentioned he had boxes of NOS round tubes up in the attic. I asked what he had and how much. He said it would be too much trouble to go up there to take a look but they were going to do some remodeling and then they would come down and I could have them all. I gave him my number and every time I stopped back in I would ask about them. Then the last time I went in and asked about the tubes he said they got them down the previous week and threw them out. Gee, thanks. I wasn't the biggest spending customer but he knew someone was interested. One of the kids then made a comment about how they popped when he threw them in the dumpster. I aways wondered what could have been up there.

Paul