Tube Testers and Electron Tube Equipment
Answers to RF Cafe Quiz #56

Return to RF Cafe Quiz #56

This quiz is based on the information presented in Make Your Own Tube Testers and Electron Tube Equipment, by Gary Steinbaugh.

Note: Some of these books are available as prizes in the monthly RF Cafe Giveaway.

With more than 30 years of RF engineering experience and Ham radio involvement, Gary has a very broad and deep proficiency in electronics. His new book, Make Your Own Tube Testers and Electron Tube Equipment, is a great assimilation of his personal knowledge and includes some of the highest quality line drawings and photographs of any technical book I have ever seen - and I've seen a lot of them! The preface section is also unique in nature, followed by a short history of and basic circuit design principles for vacuum tubes. Gary also conceived of and built a 3-dimensional physical model of the plate, transfer, and constant current characteristic curves for a typical vacuum tube (6SN7); you've never seen this before. The homebrew tube tester and power supply projects described in the text and built by Gary are exceptional examples of craftsmanship.

1.  Which of the following are negative properties of vacuum tubes?

a) and c)

See page 1 for a complete list of vacuum tube and transistor disadvantages

2.  Which of the following are negative properties of transistors?

c) and d)

See page 1 for a complete list of vacuum tube and transistor disadvantages

3.  Who received the first U.S. patent for an electronic device?

c)  Thomas Edison

On October 21, 1884, Edison was awarded patent number 307,031 for his "Electrical Indicator" diode.  (see page 5)

4.  What is a "bogey" vacuum tube?

a)  A theoretically "typical" tube statistically centered in the distribution of datasheet specifications.

Performance data was taken on a very large number of production tubes and the "bogey" tube was defined by the results. Today we speak of "typical performance characteristics."  (see page 9)

5.  What is the most common type of gradual failure in a vacuum tube?

d)  Low cathode emission (aka cathode depletion)

Cathode depletion occurs when the cathode is no longer capable of emitting enough electrons to replenish the space charge.  (see page 41)

6.  What are the two basic types of serviceman's vacuum tube testers?

b)  Cathode emission measurement only, and both cathode emission and amplification measurements

Service testers were intended to help spot bad tubes as quickly as possible, not to make accurate measurements of tube parameters.  (see page 46)

7.  What is a typical vacuum tube filament temperature?

b)  800° C  (~1,500° F)

Tube filaments need only to become hot enough to to provide adequate thermionic emission - about 800° C, depending on the materials used to coat the cathode: thorium, barium, strontium, etc.  (see page 40)

8.  What is a sesquimultiplier?

d)  A circuit that multiplies voltage by 1.5

Gary developed a custom topography to obtain a voltage multiplication factor of 1.5 in order to increase the options of available voltages beyond those obtainable by common voltage doublers and triplers. He dubbed it the "sesquimultiplier." The prefix "sesqui" means one and a half.  (see page 102)

9.  Why are "operational amplifiers" (aka "opamps") named thus?

a)  They were originally part of circuits for performing mathematical operations

Op amps were developed to perform mathematical operations, such as additions. subtraction, multiplication, division, integration, and a host of nonlinear functions, in the days before digital computers.  (see page 145)

10.  What is the word used to the measure of how significant the space charge effect is on the beam's motion ?

c)  Perveance

Perveance is the name given to the measure of how well the space charge of a vacuum tube conducts at a relatively low plate voltage when the tube is connected as a diode.  (see page 33)

Posted January 1, 2014