6P9P

The 6P9P in the preserved Chinese sheet is an indirectly heated oxide-cathode output pentode for video and power amplification. The document illustrates both an external metal covering and an exposed glass-envelope construction. High transconductance and available power curves are of technical interest, but do not justify automatic identification with other valves or an invented application in a particular commercial amplifier.

The heater requires 6.3 V AC or DC at 650 ±50 mA. Main characteristics apply at anode 300 V, screen 150 V, control grid −3 V and third grid zero: anode current 30 ±10 mA, screen current 6.5 ±2.5 mA and transconductance 11.7 ±2.5 mA/V. The main table also gives output power not less than 2.4 W; an invented load or distortion figure must not be added to that line. Application curves state their own measurement conditions separately.

Input capacitance is 13 ±2 pF, output 9.5 ±1 pF and transfer no more than 0.06 pF. The document includes anode and screen current versus control, anode characteristics with maximum dissipation marked, and triode-connected curves. Those belong to a configuration different from normal pentode operation: their presence does not make the modes identical.

One application graph plots output and distortion versus load at anode 300 V and screen 150 V; another plots power versus input signal at −3 V bias and 10 kΩ load. No extra numerical points were estimated from curves. Limits are maximum anode and screen voltage 330 V, anode dissipation 9 W and screen dissipation 1.5 W. Heater voltage must remain 5.7–6.9 V; DC cathode-heater voltage is limited to ±100 V. These are limits, not simultaneous operating conditions.

The base is octal. The drawing assigns 1 third grid and external shield, 2 and 7 heater, 3 unconnected, 4 control grid, 5 anode, 6 screen and 8 cathode. Anode on pin 5 requires checking the circuit, not transferring another octal pentode's wiring. The illustration states maximum height 95 mm and maximum outside diameter 34 mm. Dimensions were recorded against the sheet, without assigning an unprinted maker or confusing the outside envelope with glass alone.

Documentation consulted: Chinese 6P9P technical sheet, six pages numbered 109–114, with description, electrical data, capacitances, limits, illustrations, connections and pentode- and triode-operation curves.