6AR6WA

The 6AR6WA, presented by Tung-Sol under the dual designation 6098/6AR6WA, is a rugged beam power tube. The manufacturer calls it a beam pentode and stresses relatively high peak plate currents even at negative grid potentials. Explicit applications are industrial and military communications equipment, including airborne equipment exposed to shock and vibration. It is described as electrically equivalent to the 6AR6, with additional production-average controls and mechanical tests; family relationship does not remove the need to check connections and circuit conditions.

Indirect heating is 6.3 V, 1.2 A, AC or DC, any mounting position. The typical class-A1 pentode-connected point uses 250 V plate and screen, −22.5 V grid, 77 mA plate and 5 mA screen current. Approximate plate resistance is 21 kΩ, transconductance 5.4 mA/V and maximum grid-circuit resistance 100 kΩ. Triode connection, screen tied to plate, has a separate point: 200 V plate, −12.5 V grid, 90 mA plate current, approximately 1 kΩ plate resistance and 6 mA/V transconductance. The table gives no audio output power for these points.

Absolute maxima have separate class-A and class-B columns. Maximum DC plate voltage is respectively 400 and 600 V; maximum DC cathode current 125 and 60 mA. Both columns limit screen voltage to 315 V, plate dissipation to 21 W, screen dissipation to 3.5 W, heater-to-cathode voltage to ±200 V and bulb temperature to 225 °C; heater voltage is 6.3 V ±10%. Only the class-B column also lists maximum peak forward plate voltage 1,250 V. This is not a DC supply voltage, and 21 W is dissipation, not delivered output.

Selection specifications distinguish individual tubes from production averages. Under the specified test conditions, initial individual plate current may be 55–100 mA while the production average is controlled to 68–86 mA; transconductance ranges are respectively 4.3–6.5 and 4.975–5.825 mA/V. These are not four typical operating points. Documents include shock, vibration-fatigue, audio-noise, insulation and low-pressure breakdown tests. The 500-hour life test is a test procedure, not a guaranteed useful life or expiry time. A note also warns of possible difficulties after prolonged operation with very small cathode current.

The octal base has six fitted pins, low-loss phenolic construction and diagram 6BQ. Bottom view: cathode 1, plate 3, screen 5, heater 6 and 8, control grid 7; positions 2 and 4 have no functional pins in the drawing. This is not the usual arrangement of many other octal output tubes. Maximum dimensions are diameter 1 7/16 inches, 36.5125 mm, overall height 3 15/32 inches, 88.10625 mm, seated height 2 29/32 inches, 73.81875 mm. Documentation: Tung-Sol, 6098/6AR6WA Premium Tube, two four-page collections with characteristics, specifications, notes and curves; dated sheets include November 1, 1955 and notes January 1, 1957.