NOS is subject to interpretation and there is no specific definition for it either. There are suggestions and opinions. Tube testers do not test for these problems in the manner in which you think, except to the extent that a tube tester with sensitive leakage detection will find far more “noisy” tubes than a tube tester with only “fair” leakage sensitivity, to the extent that the noise is due to this problem.
eBay
Reference tube is tested first then the tube listed for sale. Test procedure.
eBay
Top is 6F8G 6C8G. If want to try 6F8G 6C8G. Bottom is 6SN7 6SL7 CV181 6N8P 6H8C 5692 B65 ECC32 ECC33. Amplifier design use 6SN7 6SL7 CV181 6N8P 6H8C 5692 B65 ECC32 ECC33. Top ceramic socket with gold pin for long life.
eBay
RCA 6SL7GT VT-229 Black Plate Tested 1700/1750 mhos gm No gas shorts grid emissions
eBay
SILVER ANODE, SIDE GETTER. SHORT BODY, WITH LARGE BASE.
eBay
Lot of 7 x 6SL7GT 6H8C Valves Tubes. SOVTEK, Made in Russia. Fully Tested on AVO VCM 163.
eBay
• The highest leakage current between the cathode and the heater. 20 µa. • Anode current. Of 2.3 ±0.9 mA. • The capacity input of the first triode. 3 pF. • The capacity input of the second triode. 3,4 pF.
eBay
Tube testers do not test for these problems in the manner in which you think, except to the extent that a tube tester with sensitive leakage detection will find far more “noisy” tubes than a tube tester with only “fair” leakage sensitivity, to the extent that the noise is due to this problem.
eBay