9U8

9U8 is also designated PCF82.

Description

The 9U8 is a combined high-frequency pentode and triode with high transconductance, intended for use in television receivers as a mixer (pentode) and oscillator (triode), or both systems as a multivibrator. It is an all-glass miniature tube with nine contact pins on a base. The two systems are independent and shielded from each other, and the cathodes of both systems are brought out to separate pins on the base. The TESLA PCF82 datasheet states that the tube replaces the foreign type 9U8.

Construction

The 9U8 has indirect heating with an oxide cathode, for series powering by direct or alternating current. The heater voltage is 9.5 V and the heater current is 0.3 A. The warm-up time is 16 s.

Ratings

The datasheet lists maximum heater-cathode voltage as 220 V (positive) and 90 V (negative) for each unit, and the maximum external resistance between cathode and heater as 20 kΩ. The maximum heater voltage during warm-up is 14.3 V. Maximum plate dissipation is 2.8 W for the pentode unit and 2.7 W for the triode unit. The maximum grid No. 2 voltage is 300 V, with a maximum cold grid No. 2 voltage of 550 V, and the maximum grid No. 2 dissipation is 0.5 W. Maximum cathode current is 20 mA for each unit, and the maximum control-grid circuit resistance is 1 MΩ for each unit.

Characteristics

At an anode voltage of 150 V and a control-grid bias of -1 V, the typical pentode characteristic shows an anode current of 18 mA, transconductance of 8.5 mA/V, internal resistance of 4.7 kΩ, and screen-grid amplification factor of 35. Under the same anode voltage and bias conditions, the typical triode characteristic shows an anode current of 10 mA, transconductance of 5.2 mA/V, and internal resistance of 400 kΩ.

Capacitance values given in the datasheet include: pentode input capacitance 5 pF, pentode output capacitance 2.6 pF, pentode grid-to-anode capacitance 0.01 pF, pentode heater-to-cathode capacitance 2.6 pF, triode input capacitance 2.5 pF, triode output capacitance 0.4 pF, triode grid-to-anode capacitance 1.8 pF, and triode heater-to-cathode capacitance 2.5 pF.

At f = 100 Mc/s, the datasheet gives the pentode equivalent noise resistance as 320 Ω and the pentode input resistance as 5 kΩ. The triode equivalent noise resistance is given as 1 kΩ and the triode input resistance as 4 kΩ at f = 100 Mc/s.

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 9U8, hosted by Frank Philipse's Electron Tube Data sheets.

Documents held here and used to write this page.

• 9U8
• MINISTERSTVO PŘESNÉHO STROJÍRENSTVÍ (filed under PCF82)