2x TESLA ECC803S (CV4004 E83CC) Long Plate lk Siemens E83CC 1960 Prototype Serie
2x TESLA ECC803S (CV4004 7025 ~5751), Prototype Series, 100%+/Matched, 122+128.where a new/unused tube should have S/gm = ~1.60 mA/V, good value for transconductance starts at 1.2 mA/V. Selected from a larger lot of NOS tubes.