Original poster: "Herwig Roscher by way of Terry Fritz <twftesla-at-uswest-dot-net>" <herwig.roscher-at-gmx.de> Hi fellow VT coilers, I would like to know the difference between 3-1000Z (data available) and 3-1000H (tube available). Unfortunately the search engines proved being "search" engines instead of being "find" engines. Could somebody help me please? Which search engines could you recommend? Herwig