37 RCA branded Philco used/good 1940”s (6.4ma)

37 RCA branded Philco used/good 1940”s in WB

6.4ma

Gm=1000

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)