Surface conditions and stability of characteristics in screened-grid tubes

✍ Scribed by Paul L. Copeland

• Publisher: Elsevier Science
• Year: 1933
• Tongue: English
• Weight: 408 KB
• Volume: 216
• Category: Article
• ISSN: 0016-0032
• DOI: 10.1016/s0016-0032(33)90912-6

✦ Synopsis

The characteristics of screened-grid tubes are discussed and the influence of secondary emission is emphasized. The marked change in secondary emission with surface contamination causes instability of characteristics. Experiments with carefully evacuated '24 tubes indicate that the evaporation of active material from the cathode considerably increases the secondary emission from the plate and that the liberation of "getter" in a completed tube limits the stability attainable.

Schottky i introduced multiple-grid tubes and discussed their action. Hull and Williams 2.3 experimented further with such devices and pointed out uses destined to find wide application in amplifier work. Previously Hull 4 had developed the dynatron, a tube utilizing the secondary electrons from the anode of a valve. The influence of secondary emission was quite apparent in the characteristics of the screened-grid tube discussed by Hull. 3 A widely used device involving these principles is the type '24 tube.