Ken-Rad Tight Matched Pair (2) 2A3 tNOS AT1000 TESTED Vacuum Tubes greyglass dual flat plate hifi Power Triode 1933-1936

This listing is for a Tightly-Matched (4% in plate current) Pair (2) of Ken-Rad-made 2A3 hifi Power Triode vacuum tubes in the ST (Coke bottle) tube shape. They have a black UX4 4-pin base, grey or black glass from a coating used as an RF shield in early tubes, dual flat black plate, and bottom D getter. Some of our stock is re-labeled or marked with the OEM of FordGM, Tung-Sol, GE. If you're looking for a particular brand, please message right as you order - we pack and ship quickly!

These tubes have been selected to match one another for optimal performance! Matching is based on plate current for power tubes, voltage drop for rectifiers, and transconductance (Gm) for other tubes.

Your tubes have been fully tested on a computer-regulated, USA-made 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 by the power tubes: The plate current must measure between 48 mA and 72 mA AND transconductance must measure between 4160 uMhos and 6240 uMhos, consistent with original 1933 RCA, Western Electric, Sylvania, GE, and/or Tung-Sol datasheet specifications for new tubes of this type. The tubes must also show no shorts, show a gas current less than 6 mA, and a heater-to-cathode leakage of less than 10 microamps (10 uA). The tubes 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 tNOS or Used Good 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 tubes you will receive. If a box or boxes are in the photos, you will get them. If test results appear in the photos, look close, because those are the test results of the tubes you will receive! SKU 2A3-188-5mp. Please note that matching is nearly always possible for us from stock that is inventoried but not yet listed. If you need a matched pair or quad etc., please use the make-an-offer feature through Reverb. Matching requires an extra burst of effort, so please add $5 per tube to your offer for 10% matching and $10 per tube for 4% matching. [Matching is based on plate current for power tubes, voltage drop for rectifiers, and GM for all other tubes. If you also require the label or internals to match, please specify that in your offer.]