1 matched pair) 6BL7GTA Sylvania branded GE NOS 1967-1968

1 tube) 42.5ma/39.5ma Gm=7500/7400 

1 tube) 40.2ma/43.2ma Gm=7600/7950

Matched on Amplitrex

Vplate=250V

Vgrid=-9V

Good Ma = 32-40ma

Good Gm = 6200 - 7000

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)