Pair By Gm M8137/ecc83/12ax7 Mullard Grey Plate O Getter Tested Roetest V10 Nos

PAIR BY GM M8137/ECC83/12AX7 MULLARD GREY PLATE O GETTER TESTED ROETEST V10 NOS. 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. Rebranded Zaerix, they look exact like MULLARD.

Tubes NOS/NIB, never used, Tubes and boxes look impeccable. Tested With Roetest V10 By GM NOS/NIB. 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. I =1.53mA I =1.5mA.

I =1.59mA I =1.59mA. 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.