Tubes for RF Heating

196 Pages·1971·40.312 MB·English

by  H.F. Dittrich

PHILIPS
APPLICATION TUBES FOR
BOOK
R. F. HEATING
ELECTRONIC COMPONENTS
AND MATERIALS DIVISION

Tubes for R. F. Heating

Tubes for R.F. Heating
H. F. Dittrich
Edited by H. Stanle~~
PUBLICATIONS DEPARTMENT
ELECTRONIC COMPONENTS AND MATERIALS DIVISION
Q N.V. Philips' Gloeilampenfabrieken
EINDHO VEN -The Netherlands
February 1971
The publication of this document does not
imply a licence under any patent
Contents
Acknowledgement
Introduction
1. Tubes for R. F. Heating 3
1.1. Design Requirements 3
1.2. Tube Types 4
1.3. Envelope Construction 6
1.4. The "K" Grid 7
1.5. Electrode Construction 8
1.6. Anode Voltage Supply 9
1.7. Additional Considerations 9
1.8. Summary 10
2. H.T. Supply 12
2.1. Mains Voltage Fluctuations 12
2.2. Rectifications 12
2.3. Self Rectification 12
2.4. Power Supply Ripple 13
2.5. Filament Supplies 13
2.6. Anode Voltage Supply 18
3. Cooling Systems and Temperature Measurements
3.1. Anode Cooling Systems 21
3.2. Temperature Measurements 25
4. Environmental Design Considerations 26
4.1. Interference Problems 26
4.2. Radiation Suppression 26
4.3. Frequency Stability of Oscillators 30
4.4. Safety Circuits 33
5. Circuit Techniques
5.1. Basic Oscillatory Circuits 41
5.2. Tank Circuits 51
5.3. Drive and Feedback Circuits 75
5.4. Cathode Circuits 79
5.5. Blocking Capacitors 80
5.6. Filtering Inductors 84
5.7. Supply Line Filtering 90
5.8. Parasitic Suppression Circuits 92
5.9. Earthing Points 95
5.10. Grid Biasing Circuits 96
5.11. Grid Switching Circuits 97
5.12. Arc Suppression Circuit 101
6. Load Coupling Circuits 102
6.1. Requirements 102
6.2. Inductive Loads 104
6.3. Dielectric Loads 116
7. Test Instruments and Methods 130
7.1. Grid Dip Meters 131
7.2. Neon Probes 133
7.3. Waveform Monitors 136
7.4. Panoramic Receivers 140
7.5. Power Measurements 141
8. Applications 145
8.1. Induction Heating Generator 145
8.2. Dielectric Heater Using Half-Wave Line at 30 MHz 158
Index 177
Acknowledgement
Although this book merely touches some of the problems met in the
design of generators for r.f. heating, it brings together the work of many
people active in that field.
Among the problems it deals with, a number have provided stimulus
for further development. Solutions that were technically sound as well as
economically acceptable were, in many cases, found only through close
cooperation between the user of the equipment, the designer of the r.f.
generator, and the manufacturer of the r.f. tube. Members of sales,
development, manufacturing, quality control, and applications staffs have
all participated in this cooperation. To these, and to the staff of the
development laboratory in Eindhoven, without whose active and
enthusiastic cooperation practical realization of much of the applications
work described in this book would not have been possible, the author
expresses his appreciation and heartfelt thanks. Especial thanks are also
due to his colleagues P.G. Giles, D. E. Nightingale, and C.W. Touch
who have contributed some of the chapters.