Cunningham ONE (1) CX-301A Output Triode Antique tNOS AT1000 TESTED Vacuum Tube Engraved SUPER POWERED Audio 1923-1930

This listing is for One (1) CX-301A Output Triode Antique vacuum tube in the Globe (S) tube shape. It has a engraved black 4-pin UY base, Nickel plate, and hidden getter.

This tube tested WAY beyond specs for its type, with 10.2 mA plate current and 3220 uMhos transconductance!

Your tube has been fully tested on a computer-regulated Amplitrex AT1000 on Fixed Bias setting with like new, NOS results (tNOS). Here's what that means: to qualify for this listing, several stringent conditions must be met: The plate current must measure between 2.4 mA and 3.6 mA AND transconductance must measure between 640 uMhos and 960 uMhos, consistent with original 1923 RCA, Sylvania, GE, and/or Tung-Sol datasheet specifications for new tubes of this type. The tube must also show no shorts, show a gas current less than 0.3 mA, and a heater-to-cathode leakage of less than 10 microamps (10 uA). The tube might have mechanical wear or have the label rubbed off - these are very old! Used-testing tubes are available in a separate listing at a significant discount. Every tube you receive from Sound By Doc is guaranteed against failure for 60 days after purchase, an industry extreme!

These photos are not stock photos. You are looking at the actual tube you will receive. Serial Number L-0705.