ECC803S is a double triode of special quality with separated cathodes and big amplification factor. Available tube is genuine Tesla tube made in the former Czechoslovakia in year 1966 (KT code). High reliable tube with tight tolerances, vibration and shock proof, long service life (over 10 000 operating hours under prescribed conditions). NOS tube directly from the old surplus. Tube is fully tested with RoeTest V10 tube tester. Testing protocol of actual tube is in the gallery. Tube will be delivered in a modern white box, testing protocol is included.