TESTED WITH ROETEST V10 BY CURVES LONG PLATES. Rebranded Zaerix, they look exact like MULLARD. Tubes NOS/NIB, never used, Tubes and boxes look impeccable. ECC802S is the best option, the highest quality tube available to upgrade from any ECC82 series tubes.Long plates, see difference in pics. Telefunken datasheet delive r d etailed improved specifications for ECC802S compared with usual ECC82. 1 Ia = 8.7 ÷ 12.3 mA typical 10.5mA.
2 S = 1.8 ÷ 2.6 mA/V typical 2.2 mA/V. 3 Ri = 7.7 k? For tubes we sell in this listing we measured all 5 parameters mentioned (and many other tests), results are excellent, with tube is delivered full test protocol with data and curves. Conditions for test: 250V/fix bias -8.4V. Zaerix was the brand name of a company called Z and I Aero Services, an important suppliers to government and military contracts.
They did not make valves themselves but they did source high quality valves from manufacturers around the world and ensured they met their high standards. Tested with Roetest V10, "the Rolls Royce of tube testers" [emissionlab quote], a wonderful german professional system for testing tubes, it shows everything about a tube. If you have experience in the field of tubes you can find in the photos and in the details below the testing / sorting procedure and all the results, and if you do not have the necessary experience to understand what is explained you can trust that we deliver only very good tubes.The best method of selecting tubes in pairs is to overlap the G1/Ia curves, the superimposed curves show us that the tubes have the same plate current and the same transconductance in the whole operating range. One point matching method used with analog tube testers is a pretty good compromise solution, but identical tubes at one point can have big differences at higher or lower currents, testing in 20÷50 points with these devices and drawing curves take hours for each tube. Roetest does this quickly and with great precision. This is the best way to select pairs, based on overlapping curves. The tubes meet datasheet specifications, first the quality tests - filament test, shorts test, gassy test (Ig1, vacuum factor, Ia variation with 1M2 grid series resistor), kathode isolation (leakage to filament), then quantity tests - value of current for plate, kathod, G1, value for transconductance, gain, G1 curve, Ia curve etc.
All results for these tests can be seen on te datasheet delivered for each tube. Those who use tubes are more familiar with terms like bias, gain (µ), plate current, slope/transconductance, and maybe someone is wondering what the term "D of plate" in the measured data means. Its value in itself is not so important but it is useful to calculate the other parameters taking into account. S x D x Ri = 1 (slope penetration internal resistance=1), where D is -dUg/dUa at Ia=const. Barkhausen vas a german physicist.He was "the guru" of tubes, his theory and formulas guided the entire period of electronic tubes. If you have any objections please contact me for a specific quotation.