RCA etc. ONE (1) Type 27 Triode Antique tNOS AT1000 TESTED Vacuum Tube Audio 1930-1940

This listing is for One (1) Type 27 Triode Antique vacuum tube in the ST (Coke Bottle) tube shape. It has a black 5-pin UY base, black plate, and bottom getter. Labels in stock include RCA, GE, Philco, Tung-Sol, Raytheon, Zenith, NU, Sylvania. If you're looking for a particular brand, please message right as you order - we ship quickly!

Some have engraved bases.

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 4.2 mA and 6.2 mA AND transconductance must measure between 780 uMhos and 1170 uMhos, consistent with original 1930 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 0.52 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!

OPTIONS (use Reverb offer function):

Want a regular white box? $1 extra
Want a tube that's packed in its original box? $3 extra per tube
Want the test results recorded on your box, too? $3 extra
Want two tubes that match one another within 5% for emissions and GM? $5 extra per tube