Philips JAN 12AX7WA Tube NOS / NIB (Internally balanced)!!! - $40 - (Hutchinson, KS)
Internally balanced Philips ECG JAN 12AX7WA Preamp Tube New Old Stock / New In Box / Never Installed / Never Used Philips ECG JAN (Joint Army Navy) 12AX7WA preamp tube. These are new old stock tubes, in their original boxes, and they have never been installed or used. On the glass of the tubes it reads in green: JAN 12AX7WA, Philips ECG, 8252, AGC, 34167, and USA. Near the top of tube in gray it reads 12AX7WA USA. The boxes are printed on one side as follows: 5960-00-827-8782, JAN 12AX7WA, 1 EA. ELECTRON TUBE, DLA900-82-C-3601, A 11/82. On the lid of the box is JAN 12AX7WA. Included are the curve traces for this tube. My curve tracer can plot the operational curves for both internal triodes simultaneously on the same plot. One triode is plotted with a solid line whilst the other is the dashed line. When the plot of both triode sections are identical, the tube is considered perfectly balanced and both sections will perform identically. Seeing IS believing; this tube is quite unique in that both internal triode sections are so perfectly matched! Each triode section has 2550/2500 uMhos of transconductance!!! Do the math: Transconductance = (Change in plate current * 1000) / change in grid voltage Example:1ma of plate current with a grid voltage of 2vand 6.1ma of plate current at a grid voltage of 0v((6.1 - 1) * 1000)/(2-0) or 5100/2 or 2550uMhos! Both of the internal triode sections exhibit nearly identical curves. This is a very nicely balanced tube. I use a uTracer3 vacuum tube curve tracer, also pictured, at least the business end of it is.
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From ebay.com - 1 month ago