Matched Pair Amperex 6BL8 Vacuum Tubes 7199 Substitute JJ NOS-Testing This tube has steel support

This tube has steel support rods

They measured 30/34 and 38/37 where minimum (65%) is 25/25 and 100% is 38/38

The Superior-tested tube measured "low to medium-good

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Matched Pair Amperex 6BL8 Vacuum Tubes 7199 Substitute JJ NOS-Testing This tube has steel supportThis matched pair of French Amperex 6BL8 pentode triode tubes was tested on our Paul Hart calibrated TV7 U for shorts, gas and transconductance. There were no shorts or gas. Transconductance measured 38 39 for Tube One and 41 35 for Tube Two where minimum (65%) is 34 36 and 100% is 52 55. As I write, I am listening to them with adapters in my Dynaco Stereo 70. They make excellent 7199 substitutes and sounded great in my amp. They were played with