TV-7 Controversy: Are TV-7 Tube Testers Worth Trusting?

Are TV-7 tube testers accurate? Are they worth trusting? According to the US experts on these kinds of mutual
conductance measuring tube testers, they are obviously not very accurate testing devices in a very strict sense. For one thing,
remember that they were produced on OEM basis at numerous manufacturers throughout the United States, at Stark Electronics
in Canada,and strangely enough, even in Germany.Even though the fundamental circuit and structure designs are evidently carried
out by Hickok Instruments, Ohio, USA, slightly & delicately different parts are used for the assembling of these TV-7 series
tube testers, and also according to the year they were produced, their specifications seem to be different.As Mr. Daniel J Nelson
points out, each carefully calibrated TV-7 tube testers' reading is different, as much as plus/minus six percent. A Japanese ham radio
operator, JA8FDT, living in Hokkaido Japan, used to be a F-104 fighter plane pilot when young, and was trained to repair and maintain
TV-7 tube testers in the past, says that the tolerance of these kinds of tube testers is plus/minus ten percent. Besides, he says,
the device was intended to be used by GI Joes who were not always well-educated. They are very easy to handle without much
knowledge, and as a result they are not extremely accurate. Okay, I accept all you say, but then am I to believe what their
readings on the meters show. I can safely say that they perfectly reflect the quality of a good vacuum tube or a bad vacuum tube all
right. I have a couple ofemission testing tube testers at hand, like Century FC-1, Century FC-2, and Heathkit TC-2 tube testers,
also have had EMC 625, Accurate 157 and lots of types of tube testers in the past. If those emission type tube testers tell me
that a tube is bad, and the tube in question is also shown as bad on TV-7 tube testers, and they are even stricter in their appraisal of
the tube. So in spite of different linearity of quality meters on TV-7 tube testers, and its subsequent difference in meter reading,
still TV-7 tube testers will continue to be loved by expert tube lovers as well as beginners.
The reason why TV-7 tube testers are always loved by hobbists as well as experts worldwide is that their tube data book is the most
elaborate treasury that covers almost all the existent vacuum tubes in the world, and except for extreme high-power transmitter
tubes, like 3-500Z, 4CX-1000B, etc even small power transmitter tubes can be tested on TV-7. I even found a tube datum for
4X150B on one of the TV-7 tube testers I purchased from the United States.
Philip
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