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September 1945 Radio-Craft
 [Table of Contents]
Wax nostalgic about and learn from the history of early electronics.
See articles from Radio-Craft,
published 1929 - 1953. All copyrights are hereby acknowledged.
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Once mobile and other high-vibration
and impact operational environments became the norm for communications, it became
necessary to design hardware so that electronic components would not work themselves
loose and cause intermittent or total failure. With vacuum tubes, placing locking
shields over them did the job, but that caused other issues such as increased cost,
 poor cooling, and increased chassis size
and weight. Some circuits with high power and/or frequency benefited from shields,
but most did not need them. Sylvania introduced a scheme called "Lock-In" (trademark
name of "Loktal")where the center pin incorporated a circumferential groove that
latched into a capturing mechanism. It was strong enough to keep the tube properly
seated but loose enough to be easily removed during servicing. Some models exploited
the heavier metal contact for use as an electrical element. The downside was that
although the pinout fit the standard octal base (8 pins), the contact diameters
were smaller than standard pins (in order to facilitate higher frequency operation)
so they made poor contact in standard octal sockets.
Sylvania News Radio Service Edition
 Sept. Published by Sylvania
Electric Products, Inc., Emporium, Pa. 1945
Wide use of "Lock-In" Tubes by the Military Seen Influencing Set Design
Repairmen Should Prepare For Servicing High Frequency Sets Carrying These Tubes
The armed forces have been using millions of Sylvania Lock-In Tubes of various
types. During 1944 alone, millions of a single type tube, of lock-in construction,
were supplied.
Why? Because the mechanical and electrical features of the Sylvania Lock-In are
better, more rugged than any other tube made. Most important is the fact that, because
of this electrical perfection, the lock-in can handle high and ultra-high frequencies
much more efficiently, as necessary for FM and television.
Because of this special construction the Lock-In Tube has no trouble taking
in its stride the recent FCC assignment of the band between 88 and 106 megacycles
to frequency modulation. In fact it is right in step with the continuing trend of
the industry toward higher frequencies.
Yes m'am, I carry those radio tubes especially made for this high frequency set.
Sylvania Serviceman Service
Frank Fax
One of the most direct sources of information about the industry, particularly
for radio servicemen, is Sylvania Electric's well-informed 8-page monthly bulletin
- Sylvania News.
This interesting and helpful paper was started in the early 1930's for the purpose
of supplying repairmen with a handy reference file that would contain past and current
news of those items that would benefit them most.
Many features of special interest to radio servicemen are dealt with, making
the 8-page Sylvania News a really helpful bulletin for repair shops all over the
country.
Subscriptions are free to radio servicemen. To have your name placed on mailing
list, just write to Frank Fax, Sylvania Electric, Emporium, Pa.
Lest We Forget
This Stands for Honorable Service to Or Country
Sylvania Electric
Emporium, Pa.
Makers of Radio Tubes; Cathode Ray Tubes; Electronic Devices; Fluorescent Lamps,
Fixtures, Wiring Devices; Electric Light Bulbs
Posted August 25, 2020
(updated from original post on 8/19/2014)
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