Description

4 x 12AU7A Sylvania Tubes Made in USA for Hammond Long Grey plates O getter Lettering may be smudged/missing Looks like 1960 codes - hard to read The auction is for 4 tubes Tested on Enhanced Tripplet E3444 Laboratry Tester prepared by Paul Hart Results = 2240/2450 micromhos @ 9.3/12.1 mA 2310/2300 micromhos @ 10.0/9.9 mA 2340/2390 micromhos @ 9.8/10.3 mA 2390/2320 micromhos @ 10.0/9.9 mA Bogey(100% or new) = 2200/2200 micromhos @ 10.0/10.0 mA +/- 10% I do combine S&H 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?