THE HISTORY OF TUNGSRAM 1896-1945 - MEK

K •205 TUNGSRAMBefore the mass-production ofelectronic vacuum tubes—in 1920,for example—experimental prototypesof the various designswere made in small series. Someof them are shown in the nextpictures. The pear-shaped tube isobviously one of the direct predecessorsof the H2 and H3.The tubes shown here were designatedas H2 and H3. These werethe first two radio valves whichwere produced by TUNGSRAM inlarge quantities. These tubes hadtungsten filaments and consumedonly slightly more energy than twoflashlight lamps. Of course, theirluminous intensity was also in thesame range. They had a transconductanceof 0.3 mAA/.' f - ,•r-