7643 Valvo branded Amperex PQ Germany “”PINCHED WAIST”” NOS 1960 (6BL8 sub) Title: 7643

7643 Amperex Germany “”PINCHED WAIST”” NOS Gold Pins made by Valvo Hamburg Germany (BG2-D0J1=1960) date code on bottom of tube (Triode/Pentode)

triode) 11.5ma Gm=4600

pentode) 7.0ma Gm=5400

Good Triode section Ma and Gm = 10-13ma Gm= 4500-5000

Good Pentode section Ma and Gm = 9-11ma Gm = 6000-6500

(The E80CF is a “”SPECIAL QUALITY”” medium-mu triode/pentode. Specs are similar to 6BL8=ECF80)

– McIntosh MR-67 tuner