February 1931 QST
Wax nostalgic about and learn from the history of early electronics. See articles
QST, published December 1915 - present. All copyrights hereby acknowledged.
Visit the ARRL
website today for a complete digital archive of QST
and their other publications.
Vacuum tubes all required some level of hand assembly by human workers, at least for positioning grids and attaching/routing the leads to external connection pins. A 1940s vintage film titled "Electrons on Parade" made by RCA shows how laborious the process was. Tubes like this Radiotron UV-861 required a human glass blower to form each one individually, as opposed to standard tube shells being machine-blown.
RCA Victor Company Radiotron UV-861
A screen-grid 500 watt R. F. Power Amplifier
The best operation of any power circuit is assured when it is equipped with RCA Transmitting Radiotrons. This is because:
1. They are the result of the longest experience in the commercial manufacture of power tubes.
2. They are the product of the world's largest and most famous radio engineering laboratory.
3. They are guaranteed to be free from electrical and mechanical defects.
When you use RCA Transmitting Radiotrons, therefore, you get long service and the maximum quality of performance.
Radiotron Type UV-861 (illustrated above) is particularly recommended for high frequency use as a linear (Class B) amplifier. The fourth electrode - the screen - makes neutralization unnecessary.
Filament Volts 11 Filament Amperes 10
Amplification Factor 300
Linear RF Amplifier-Class B
Normal Operating Plate Volts 3000
Screen Voltage (Approximate) 500
*Control Grid Bias Voltage - 60
Non-modulated Plate Current (DC) 188 M. A.
Peak Power Output 600 Watts
Carrier output (100% modulated) 150 Watts
*Referred to midpoint of filament
Additional technical data will be furnished upon request.
Engineering Products Division
RCA Victor Company, Inc.
Camden, New Jersey
155 East 24th Street New York City
100 West Monroe Street Chicago, Ill.
Santa Fe Building Dallas, Texas
235 Montgomery Street San Francisco, Calif.