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.
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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
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
Screen Voltage (Approximate)
*Control Grid Bias Voltage
Non-modulated Plate Current (DC)
188 M. A.
Peak Power Output
Carrier output (100% modulated)
*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.