Amperex 6DJ8 tNOS AT1000 TESTED Balanced! PI Vacuum Tube HP Selected Heerlen ECC88 dual triode 1962-1973

This listing is for one (1) Amperex-made 6DJ8 ECC88 dual triode vacuum tube in the standard tube shape. It has a B9A 9DE noval 9-pin base, grey plate, and halo or dimpled disc getter.

Selected for HP or BT Labs by Amperex or tested by Tektronix. These are T3 T4 or T5 made in Heerlen, Netherlands with the Heerlen triangle etched in the glass. SoundByDoc has classified five main types of Heerlen ECC88: T1 (1957): Ultra rare pinched waist, D getter. T2 (1958-1959): D getter GA0 GA1 GA2 code. T3 (1959-1962): Large halo getter GA3, GA4, GA6, and some GA7. T4 (1962-1968): Small halo getter GA7, GAA, GAB, GAC. T4bb: same as T4 but with at least some of the bugle boy logo visible. T5 (1965-1972): Orange Ink, Dimple Getter, or A-frame getter support (any or all of these qualities makes it a T5).

This tube has been tested to be perfectly balanced in transconductance (Gm) between the two sections. It is appropriate for phase-inverter positions and other demanding roles.

Your tube has 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: The transconductance for each section must measure between 10000 uMhos and 15000 uMhos, consistent with original 1962 RCA, Western Electric, 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 1.5 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 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 tube 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 tube you will receive! SKU 6DJ8-423SELPI. 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.]