The 6BM8 is an audio triode plus output pentode of seven Watt anode dissipation. The output section is a beam tetrode rather than a pentode.
The triode section has a amplification factor of 70, and this valve was much used in record players with crystal pickups. The latter had a relatively high output and when coupled with the single ended pentode output stage made effectively a single valve design. Only a rectifier was required to complete the line-up.
The Toshiba logo and Japan. Inside is the beam tetrode and the bright screen separating it from the triode.
The triode grid axis is set at 90° to the power output section.
The full company name - Tokyo Shibaura Electric
The thin glass tube envelope is 20 mm in diameter and excluding the B9A base pins the valve is 71 mm long.
References: Data-sheet & 1040. Type 6BM8 was first introduced in 1956. See also1956 adverts.
