This Farnsworth Photomultiplier tube listed by his son on eBay
http://www.ebay.com/itm/Farnsworth-T...item258995eec8 How important is this tube in the history of Television? This is more of a Television history question then curbside posting. I have purchased several RCA and Baird photomultipliers in the $10-$15 range over the years.