NOT FOR SALE

[ Home Page ]


Zenith Model 7-D-138, 1937.  The large tombstone cabinet features seven tubes, multi-band tuning, an 8-inch electro-dynamic speaker, and voice-music-high fidelity control.
Zenith 7-D-138 Dial Face Model Number Chassis (No. 5707)
  Schematic
(About 1MB in Size)
1937 Features  

Zenith WAVEMAGNET Loop Antenna

6A8
Pentagrid Converter

Substitutes Base Diagram
6D8G*, 6A8MG, 6A8GTX, 6A8GT, 6A8G, 6D8*

Notes: * - Parallel filaments

6K7
Remote Cutoff RF Pentode

Substitutes Base Diagram
5732, 6U7G, 6K7MG, 6K7GTX, 6K7GT, 6K7G, 6U7, 6J7, 6S7

6H6
Duo Diode

Substitutes Base Diagram
WT261, WTT103, 6H6WGT, 6H6MG, 6H6GT/G, 6H6GT, 6H6G

6F5
High Mu Triode

Substitutes Base Diagram
6F5MG, 6F5GT, 6F5G

25A6
Power Amplifier Pentode

Substitutes Base Diagram
25A6MG, 25A6GT/G, 25A6GT, 25A6G, 25W6

MECHANICAL DATA

Bulb MT-8B
Base 7-Prong Octal Base
Basing 7S

ELECTRICAL DATA
HEATER CHARACTERISTICS

Heater Voltage 25.3 Volts
Heater Current 0.3 Amps

MAXIMUM RATINGS

Plate Voltage 160 Volts
Screen Voltage 135 Max
Plate Dissipation 5.3 Watts
Screen Dissipation 1.9 Watts

CHARACTERISTICS AND TYPICAL OPERATION
CLASS A1 AMPLIFIER (Each Section)

Plate Voltage 95 135 160 Volts
Screen Voltage 95 135 120 Volts
Grid Voltage -15 -20 -18 Volts
Peak A-F Grid Voltage 15 20 18 Volts
Zero-Signal Plate Current 20 27 33 Ma
Max-Signal Plate Current 22 29 36 Ma
Zero-Signal Screen Current 4 8 6.5 Ma
Max-Signal Screen Current 8 14 12 Ma
Plate Resistance (Approx.) 45000 35000 42000 Ohms
Transconductance 2000 2450 2375 ?mhos
Load Resistance 4500 4000 5000 Ohms
Total Harmonic Distortion 11 9 10 Percent
Max-Signal Power Output 0.9 2.0 2.2 Watts

 

25Z6
Rectifier Doubler

Substitutes Base Diagram
25Z6WGT, 25Z6MG, 25Z6GT/G, 25Z6GT, 25Z6G

STANDARD RMA CONDENSER COLOR CODE

THE CAPACITIES OF MANY SMALL CONDENSERS ARE DESIGNATED BY A SERIES OF THREE COLORED DOTS, STAMPED ON AN ARROW-SHAPED FORM ON THE CONDENSERS, IN ACCORDANCE WITH THE STANDARD RMA CONDENSER COLOR CODE.

THESE DOT SYMBOLS ARE TO BE READ FROM THE TAIL TOWARD THE HEAD OF THE ARROW. THE CAPACITY IS EXPRESSED IN MICRO-MICRO FARADS. THE FIRST DOT INDICATES THE FIRST FIGURE OF THE CAPACITY, THE SECOND DOT INDICATES THE SECOND FIGURE AND THE THIRD DOT INDICATES THE NUMBER OF ZEROES FOLLOWING THE FIRST TWO FIGURES.

EXAMPLE

Nostalgia Air RMA Color Code References

 


Helpful Radio Restoration Links:

Nice Audio and Electronic Links




Copyright 2004 - 2018 - Victory Radio is a Trademark of The Network Services Group - All rights Reserved


Click for Heirloom Tomato Seed Selection Seed Favors Save Seeds - Victory Horticultural Library

Please