1AJ4

1AJ4 is also designated DF96.

Description

The 1AJ4 is a coated filament pentode intended for use as an R.F. or I.F. amplifier. It has a miniature button 7-pin base with JETEC basing designation 7DP, and a T5a bulb.

Construction

The maximum overall length of the 1AJ4 is 2.205 inches, and the maximum seated height is 1.955 inches. The bulb length excluding tip is 1.580 inches ± 0.094 inches, and the maximum diameter is 3/4 inch. The tube can be mounted in any position.

Ratings

The filament of the 1AJ4 operates at 1.4 volts and draws 25 milliamps. Maximum ratings include a plate dissipation of 0.25 watt, a grid No.2 dissipation of 0.1 watt, a cathode current of 2.2 milliamps, and a grid No.1 circuit resistance of 3 megohms.

Characteristics

Capacitance values for the 1AJ4 are 3.3 µµF from grid No.1 to all other elements except plate, 7.8 µµF from plate to all other elements except grid No.1, and a maximum of 0.61 µµF from plate to grid No.1. The grid current starting point is -0.2 volt when grid No.1 current equals +0.3 µamp. At a plate voltage of 85 volts, the transconductance is 750 micromhos and the plate resistance is 0.7 megohm. At a plate voltage of 64 volts, the transconductance is 750 micromhos and the plate resistance is 1.0 megohm.

Equivalent

The German equivalent of the American type 1AJ4 is the DF96, a variable-mu pentode for use in RF and IF amplifiers. The DF96 features a directly heated oxide cathode for battery operation, can be used with parallel or series heating, and has a pentode system mounted perpendicular on a pressed-glass base. Its heater operates at 1.4 volts at 25 milliamps or 1.3 volts at 24 milliamps. The DF96 datasheet, prepared by the Zentrallaboratorium für Empfängerröhren im VEB Funkwerk Erfurt and the VEB Röhrenwerk Anna Seghers, Neuhaus am Rennweg, and issued in April 1960, lists maximum ratings of 150 volts anode cold voltage, 120 volts anode voltage, 250 milliwatts anode dissipation, 120 volts screen-grid cold voltage, 90 volts screen-grid voltage, 100 milliwatts screen-grid dissipation, 2.2 milliamps cathode current, and 3 megohms grid leak resistance. It gives an equivalent noise resistance of 14 kilohms, or 12 kilohms at an anode voltage of 45 volts, and a screen-grid amplification factor of 18. The grid current starting point of the DF96 is 0 volts when grid current is less than or equal to 0.3 µA.

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 1AJ4, hosted by Frank Philipse's Electron Tube Data sheets.

Documents held here and used to write this page.

• Regelpentode (filed under DF96)
• 1AJ4

1 further designation appears alongside 1AJ4 in the literature but below the evidence threshold used here, so it is not listed as equivalent.