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Kirt Blattenberger - RF Cafe Webmaster

Copyright: 1996 - 2024
    Kirt Blattenberger,


RF Cafe began life in 1996 as "RF Tools" in an AOL screen name web space totaling 2 MB. Its primary purpose was to provide me with ready access to commonly needed formulas and reference material while performing my work as an RF system and circuit design engineer. The World Wide Web (Internet) was largely an unknown entity at the time and bandwidth was a scarce commodity. Dial-up modems blazed along at 14.4 kbps while typing up your telephone line, and a nice lady's voice announced "You've Got Mail" when a new message arrived...

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RCA Victor Company Radiotron UV-861 Advertisement
February 1931 QST Article

February 1931 QST

February 1931 QST  Cover - RF CafeTable of Contents

Wax nostalgic about and learn from the history of early electronics. See articles from QST, published December 1915 - present (visit ARRL for info). All copyrights hereby acknowledged.

Join the ARRL Today! - RF CafeVisit 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

RCA Victor Company Radiotron UV-861, February 1931 QST - RF Cafe

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.

UV-861 Rating

Filament Volts 11       Filament Amperes 10

Amplification Factor 300

Mutual Conductance

2.25 Milliamperes/volt

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.




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