The Superior TV-12 is an excellent tester, and one of my personal favorites. Its' sibling, the TV-11, is an emission tester, but still looks very classy. The hand-rubbed oak finish is a real treat for the eyes, providing the finish was maintained over the years. A few noteworthy points on the circuit description of the TV-12:

• The ad states "... An in-phase signal is impressed upon the input section of a tube and the resultant plate current change is measured." This is actually less preferred than an out-of-phase signal, as the test signal must not be large enough to drive the grid into the positive-grid region. When this happens, the control grid conducts, and loads down the signal source. This results in less amplitude of the drive signal, leading to less plate current, and finally a lower reading on the meter! During 'normal' operating conditions, the grid should swing negative while the plate and screen swing positive. That sounds like a no-brainer, but surprisingly overlooked in some tube testers.
• The ad further states "...Amplification factor, plate resistance, and cathode emission are all correlated in one meter reading." I'd sure like to know how that's possible. If the meter movement is in series with the plate, it is measuring plate current. A typical 12AX7 might have an amplification factor of '100', have a plate current of 2mA (under certain conditions), a plate resistance of about 60K (again under certain conditions), and emit 'x' number of electrons traveling at a speed of 2,820,000 miles per second. How this all can get displayed on one analog meter movement is a mystery. (*UPDATE* I was being facetious. There is no mystery; it is simply a case of the advertising department having some fun.)
• The 'Safety Button' feature is a great idea. Hickok tube testers have a fuse in the bias circuit, which opens up if you should put a shorted tube in for testing. Why everyone did not utilize this idea is another mystery to me. I suppose the thinking was that you did a 'shorts' test before doing a transconductance test. However, I have mentioned already that simple neon indicators are only good for detecting resistive shorts of about 1 Meg. A 2 Meg resistive short between grid and cathode would not show up, read 'Good' transconductance at a plate voltage of 150VDC in the tester, and blow fuses in your Marshall.
• The ad goes on to mention "...application of separate voltages as required for both plate and (screen) grid of tube under test, resulting in improved Trans-Conductance test." This is typical of most testers, except in some rare examples where all tetrodes/pentodes are converted into triodes for testing. My Hickok 799 is one example, but again, this is rare. To me this is somewhat akin to advertising your guitar has 'Six strings, allowing the playing of fuller chord voicings and wider ranging single note lines.' There are enough good things to say about the TV12 that you do not have to waste time and advertising space with such mundane observations.

In conclusion, there is a bit of misleading advertising going on here, but that does not deter me from really liking the Superior TV-12 as a tube tester, and as a piece of fine woodworking.