10EG7 — Dissimilar Double Triode

The 10EG7 is a glass octal double triode containing two highly dissimilar triode sections in a single envelope. It is specifically designed for use in television receivers employing series heater-string arrangements. Section 1 is designed to operate as a vertical deflection oscillator, while Section 2 is designed to function as a vertical deflection amplifier.

Mechanical Specifications, Base, and Pinout

The 10EG7 is constructed with a T-9 glass bulb and utilizes a short intermediate-shell octal 8-pin base with external barriers, conforming to the JEDEC Group 1, No. B8-58 standard. The tube can be mounted and operated in any position.

Physical Dimensions

• Maximum Overall Length: 3.000 inches
• Maximum Seated Length: 2.437 inches (2-7/16")
• Maximum Diameter: 1.188 inches (1-9/32")

Pin Connections

The tube uses the 8BD basing arrangement. When viewed from the bottom of the base, the pin assignments are as follows:

Section 1 (Oscillator) is connected to pins 4, 5, and 6, while Section 2 (Amplifier) is connected to pins 1, 2, and 3.

Heater Characteristics

The 10EG7 features a series-string heater designed for operation with unipotential cathodes.

The heater warm-up time is defined as the time required for the voltage across the heater to reach 80% of its rated voltage after applying four times the rated heater voltage to a circuit consisting of the tube heater in series with a resistance equal to three times the nominal heater operating resistance.

Heater-Cathode Voltage Ratings (Design-Maximum Values)

• Heater Negative with Respect to Cathode: 200 V max (Total DC and Peak)
• Heater Positive with Respect to Cathode: 100 V max DC, 200 V max (Total DC and Peak)

Electrical Characteristics and Class A1 Operation

The two triode sections of the 10EG7 are electrically dissimilar, with Section 1 operating as a medium-mu unit and Section 2 operating as a low-mu unit. The typical operating conditions and characteristics under Class A1 amplifier service are detailed below:

Direct Interelectrode Capacitances

These values are measured without an external shield:

Design-Maximum Ratings and Television Deflection Service

The ratings of the 10EG7 are interpreted according to the Design-Maximum Rating System. These ratings represent limiting values of operating and environmental conditions that should not be exceeded under the worst probable conditions.

For operation in a 525-line, 30-frame television system, the ratings are specified as follows:

Operating Conditions and Circuit Protection

• Pulse Duty Cycle: The peak pulse ratings are applicable where the duration of the voltage pulse does not exceed 15% of one vertical scanning cycle. In a standard 525-line, 30-frame system, 15% of one vertical scanning cycle corresponds to 2.5 milliseconds.
• Grid Leak Bias Protection: In stages operating with grid leak bias, an adequate cathode bias resistor or other suitable protective means must be employed to protect the tube from excessive plate dissipation in the absence of excitation.

Related Designations

The dimensional outline of the 10EG7 is identical to that of the 6EM7. Additionally, the maximum ratings and characteristics of the 10EG7 are closely related to those of the 6EW7, except for the specific heater operating parameters.

Technical Summary

The 10EG7 is a specialized, dissimilar double triode designed for series-string television receiver applications. It combines a medium-mu triode (Section 1, \mu = 17.5) for vertical oscillator service and a high-power, low-mu triode (Section 2, \mu = 6.0) for vertical deflection amplification. Operating from a 9.7 V, 0.60 A heater with a controlled 11-second warm-up time, the tube is housed in a T-9 glass envelope with an 8-pin octal base. By separating the oscillator and power amplifier functions into distinct, optimized triode units, the 10EG7 provides a compact and efficient solution for television vertical deflection circuits.