Description

4 x 12AU7 Sylvania Tubes Made in USA Long Ribbed Grey plates D getter Etched codes L7V & A8V = 1957 Matching warranty codes 725-835 Pictures show actual Lettering may be smudged/missing Tested on Enhanced Tripplet E3444 Laboratry Tester prepared by Paul Hart 2220/2130 micromhos @ 10.5/9.8 mA 2200/2150 micromhos @ 10.1/9.7 mA 2250/2180 micromhos @ 10.7/10.0 mA 2200/2140 micromhos @ 10.1/9.8 mA Bogey(100% or New) = 2200/2200 micromhos @ 10.0/10.0 mA +/- 10% READ THIS: The measurements in this listing were taken on a Triplett 3444 modified to test the tube as an amplifier in accordance with RMA/EIA specifications, utilized by all US and most foreign tube manufacturers. This tester applies test conditions for this tube as shown below (including the precise filament voltage) and then measures trans-conductance (gm) in accordance with the engineering definition of gm. Tubes may also be operated under the test conditions for extended periods to be sure that it is stable. A tube must be tested in this manner to compare its test results with the manufacturer’s original intent or with other tubes of the same type. Most tube testers do not apply the test conditions required or conduct a valid gm test. For more details on the test and our test equipment, please contact us. The test conditions for this listing are __ 250 _Volts plate, __ 250 _Volts screen, ___ -8.5 ___Volts bias or Cathode resistance * Most other testers CANNOT test tubes using the proper specifications and make up their own test results What were your tubes tested at? I do combine S&H