37 Sylvania branded Raytheon NOS 1948 (7.0ma)

37 Sylvania branded Raytheon NOS 1948

7.0ma

Gm=900

Test parameters:

Vplate=250V

Vgrid=-18V

Iplate good range 6.5-8ma

Gm=1000-1100

(Filament=6.3V @ 300ma, many think the 37 sounds better than the 76)