6DV4 — Gold-Plated Medium-Mu Nuvistor UHF Oscillator Triode

An indirectly heated metal-shell Nuvistor designed for stable ultra-high-frequency oscillator operation in television receivers, including operation near 950 MHz.

Overview

The 6DV4 is a medium-mu Nuvistor triode intended for UHF oscillator stages in color and black-and-white television receivers. RCA specifies oscillator service at frequencies up to 1,000 MHz and provides a representative operating point at 950 MHz.

A particularly distinctive feature documented in RCA's detailed technical sheet is its gold-plated envelope and base pins, intended to provide positive grounding and low pin-contact resistance in UHF oscillator applications. This mechanical and electrical-contact detail is especially relevant at the frequencies for which the tube is intended.

The related 2DV4 has the same published signal-electrode characteristics except for its heater requirements.

Construction and Mechanical Features

The 6DV4 is a single indirectly heated triode with a coated unipotential cathode, grid, and plate in a compact MT4 metal-shell Nuvistor envelope.

It uses a medium ceramic-wafer seven-contact Nuvistor base, JEDEC E7-83, with 12EA basing. The detailed RCA drawing identifies a large index lug and shortened pin for proper orientation.

RCA assigns pins 1 and 2 to the plate, pins 4 and 6 to the grid, pin 7 to the cathode, and pins 10 and 12 to the heater. Other indicated positions are not to be used as external circuit terminals.

The published maximum dimensions are approximately 0.800 inch overall length, 0.625 inch seated length, and 0.440 inch diameter. Any mounting position is permitted.

The gold-plated envelope and base pins are intended to improve grounding reliability and minimize contact resistance at UHF, where mechanical contact quality is part of the oscillator's electrical environment.

Heater Characteristics

RCA's detailed heater rating gives 6.3 ± 0.6 V. The related 2DV4 uses 2.1 V at 0.45 A, with an 8-second average heater warm-up time. The 6DV4 family tables do not establish that the 2DV4's warm-up specification applies identically to the 6DV4.

UHF Oscillator Service

RCA specifies the 6DV4 for television UHF oscillator operation up to 1,000 MHz. Its published 950 MHz example is:

The stated grid current is an important characteristic of this oscillator operating condition. It is not the same as the low-grid-current conditions ordinarily associated with Class A1 linear amplification.

The actual oscillation frequency depends on the surrounding resonant and feedback circuit; the 950 MHz figure is a documented representative operating point.

Electrical Characteristics

RCA and Sylvania provide a Class A1 characteristic point:

The amplification factor of approximately 35 establishes the medium-mu classification. Its relatively low plate resistance and high transconductance are important in the manufacturer's specified oscillator application.

The tabulated values satisfy the approximate triode relationship μ ≈ gₘ × rₚ: 0.0115 S × 3,100 Ω ≈ 35.7.

Design-Maximum Ratings

The 300 V plate-supply figure is conditional: a sufficiently large plate-circuit resistor must limit plate dissipation to 1 W under all operating conditions. It must not be interpreted as a 300 V continuous plate-electrode rating.

RCA specifies these ratings for metal-shell temperatures up to 135°C.

Direct Interelectrode Capacitances

These capacitances are important to the design of UHF resonant circuits and oscillator feedback networks. At frequencies approaching 1 GHz, electrode and connection capacitances contribute materially to circuit reactance.

Characteristic Curves

The RCA HB3 sheet includes average plate characteristics, grid-voltage transfer curves, and plate-current characteristic plots at the rated heater voltage. These provide more information than a single tabulated operating point and support analysis of grid bias, plate voltage, and current over the published operating range.

Related Nuvistor Types

The 2DV4 is the low-voltage heater variant of the 6DV4. The DV4 family is documented for UHF oscillator service, unlike the CW4 and DS4 high-mu Nuvistor families, whose principal published application is VHF neutralized RF amplification.

The DV4 family's gold-plated construction and 12EA basing are additional reasons not to assume mechanical interchangeability with other Nuvistor families solely because they share a compact metal-shell appearance.

Technical Summary

The 6DV4 is a 6.3 V / 135 mA, medium-mu metal-shell Nuvistor triode designed for UHF oscillator service up to 1,000 MHz. RCA documents a representative 950 MHz oscillator condition and specifically identifies its gold-plated envelope and base pins as a means of obtaining reliable grounding and low contact resistance.

Typical characteristics include μ ≈ 35, 11.5 mA/V transconductance, 3.1 kΩ plate resistance, and 10.5 mA plate current. The tube has a 1 W plate-dissipation limit and a dedicated 12EA Nuvistor base.