50BM8

50BM8 is also designated UCL82.

Description

The 50BM8 is a miniature type triode-pentode designed for use as an AF amplifier by the triode section and AF power amplifier by the pentode section in radio receivers.

Ratings

The heater is rated at 50 V and 0.1 A. The maximum plate voltage is 250 V for both the triode and pentode units, and the maximum grid No. 2 voltage for the pentode unit is also 250 V. Maximum plate dissipation is 1 W for the triode unit and 7 W for the pentode unit, with a maximum grid No. 2 dissipation of 1.8 W for the pentode unit. Maximum total cathode current is 15 mA for the triode unit and 50 mA for the pentode unit. The maximum peak heater-cathode voltage is 200 V with the heater either negative or positive with respect to cathode. For the triode unit, the maximum grid No. 1 circuit resistance is 1 MΩ with fixed bias, 3 MΩ with cathode bias, and 22 MΩ with grid bias.

Typical Operation and Characteristics

In typical operation, the triode unit is run at a plate voltage of 100 V and grid No. 1 voltage of 0 V, yielding a plate current of 3.5 mA and a transconductance of 2,500 μ℧. The amplification factor of the triode unit is 70. For the pentode unit, typical operation is at a plate voltage of 100 V and grid No. 2 voltage of 100 V, with a plate resistance of approximately 15 kΩ at that plate voltage.

Capacitances

For the triode unit, the input capacitance is 2.7 pF, the output capacitance is 4.3 pF, and the grid No. 1 to plate capacitance is 4.2 pF. For the pentode unit, the input capacitance is 9.3 pF, the output capacitance is 8.0 pF, and the grid No. 1 to plate capacitance is 0.3 pF maximum.

Equivalence is asserted only where the archive's own literature states it directly, in at least 40 separate documents. Tubes that merely substitute in some circuits are not listed here.

Original manufacturer datasheets for 50BM8, hosted by Frank Philipse's Electron Tube Data sheets.

Documents held here and used to write this page.

• PHILIPS UCL82 (filed under UCL82)
• HIGH-MU TRIODE POWER PENTODE

2 further designations appear alongside 50BM8 in the literature but below the evidence threshold used here, so they are not listed as equivalent.