1 quad set) 6BL7GTA Sylvania black plates 1960”s NOS same build

1 tube) 35.2/36.6ma Gm=6800/7150

1 tube) 37.8/37.2ma Gm=7200/6900

1 tube) 34.8/38.0ma Gm=7000/7300

1 tube) 36.5/37.0ma Gm=7100/7350

Good Ma used 30-35ma

Good Gm used 6500

Recommended for

– Single Power MPX3 SE
– Cary 1610se

(Vfil=6.3V @ 1.5A, Vplate max=500V, Iplate max=60ma, Pout max = 12 watts total for both triode sides)
The 6BL7GTA is interchangeable with a 6BL7GT but differs from it in having
an improved section 1 for increased life as an oscillator, and controlled zero-bias
plate current in both sections
Typical Characteristics Class A Amp:
Vplate= 250V
Iplate= 42ma
Vgrid= -9
Rp= 2150 ohms
Mu= 15
Gm= 6200 for 6BL7 (RCA manual 1953) and 7000 mhos for 6BL7GTA (GE Manual 1957)