(!!!) (PAIR) 6HF5 Sylvania NOS 1970's (96ma and 97ma)

1 pair) 6HF5 Sylvania NOS 1970's - same plate shape - slightly different internals

1 tube) 96ma Gm=10,600

1 tube) 97ma Gm=9800 larger heat sink attached to plate - faded printing

Tested on Amplitrex

Vplate=175V

Vscreen=125V

Vgrid=-25V

Good Ma range 90-125ma

Good Gm = 9,000 - 11,000

- Diathermy machine built by Mettler Electronics