2DV4 — Medium-Mu Nuvistor UHF Oscillator Triode

Compact 2.1-volt Nuvistor for UHF oscillator service at frequencies up to 1,000 MHz in television receivers.

Overview

The 2DV4 is a medium-mu Nuvistor triode intended for ultra-high-frequency oscillator service in color and black-and-white television receivers. RCA explicitly specifies operation at frequencies up to 1,000 MHz, with a typical oscillator operating point at 950 MHz. The 2DV4 corresponds to the 6DV4 except for its heater rating.

Unlike the CW4 and DS4 Nuvistor families, whose documentation emphasizes neutralized VHF RF amplification, the DV4 family is explicitly described as a UHF oscillator tube. Its published oscillator grid-current and grid-resistor values are especially useful in understanding its intended circuit operation.

Construction, Heater, and Basing

The 2DV4 is a metal-shell Nuvistor triode requiring a dedicated Nuvistor socket. Sylvania identifies a ceramic-wafer Nuvistor base and 12EA basing. Its published dimensions are approximately 0.440 inch maximum diameter, 0.625 inch maximum seated height, and 0.800 inch maximum overall height.

The related 6DV4 uses a 6.3 V, approximately 0.135 A heater. These heater differences prevent direct substitution on an unchanged heater supply.

UHF Oscillator Application

RCA states that the DV4 triode is used in UHF oscillator stages of television receivers at frequencies up to 1,000 MHz. A representative 950 MHz oscillator condition is given directly in the manual:

This is a particularly distinctive operating example. The presence of appreciable grid current and a specified grid resistor differentiates the oscillator condition from the Class A1 small-signal characteristic table. It should not be generalized into a conventional linear amplifier operating point.

The 950 MHz example is a specified design condition, not an assertion that every circuit using the 2DV4 will oscillate at exactly that frequency. The actual oscillation frequency depends on the associated resonant circuit and feedback arrangement.

Typical Electrical Characteristics

RCA and Sylvania give the following Class A1 characteristic point:

The amplification factor of approximately 35 explains the medium-mu classification. The relatively low plate resistance and high transconductance are important electrical characteristics for the intended high-frequency oscillator service.

The characteristic values are mutually consistent with the approximate triode relationship μ ≈ gₘ × rₚ: 0.0115 S × 3,100 Ω ≈ 35.7.

Maximum Ratings

The RCA and Sylvania sheets publish the following design-maximum limits:

The distinction between 300 V plate supply and 125 V plate voltage is important. Sylvania explicitly states that a 300 V supply requires a sufficiently large plate-circuit resistor to keep plate dissipation within 1 W under every operating condition.

RCA and Sylvania give the rating context for metal-shell temperatures up to 135°C.

Interelectrode Capacitances

The manufacturer's approximate capacitance values are:

These capacitances matter in the design of resonant UHF circuits, because the tube's electrode and shell capacitances contribute to the overall circuit reactance and feedback relationships. Their measurement definitions should be retained when comparing them with values from other triode families.

Comparison with Related Nuvistors

The 2DV4 and 6DV4 share the published medium-mu UHF oscillator characteristics, differing in heater ratings:

The DV4 oscillator family should not be confused with the 2CW4/6CW4 high-mu VHF amplifier family or the 2DS4/6DS4 extended-cutoff high-mu VHF amplifier family. RCA documents different intended applications and characteristic values for these types.

Technical Summary

The 2DV4 is a 2.1 V / 450 mA medium-mu metal-shell Nuvistor triode intended for UHF oscillator service in television receivers, with published operation up to 1,000 MHz and a representative oscillator point at 950 MHz.

Its typical Class A1 characteristics include μ ≈ 35, 11.5 mA/V transconductance, 3.1 kΩ plate resistance, and 10.5 mA plate current. Its specified 1 W plate-dissipation limit, compact Nuvistor construction, and dedicated oscillator operating conditions distinguish it from general-purpose receiving triodes and from the high-mu VHF amplifier Nuvistor families.