RF Cafe Software
About RF Cafe
1996 - 2022
BSEE - KB3UON
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 Internet was still largely an unknown entity at the time and not much was available in the form of WYSIWYG ...
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July 1933 Radio-Craft[Table of Contents]
People old and young enjoy waxing nostalgic about and learning some of the history of early electronics. Radio-Craft was published from 1929 through 1953. All copyrights are hereby acknowledged. See all articles from Radio-Craft.
Here is Emerson Model 20A and 25A Radio Service Data Sheet as featured in a 1933 edition of Radio-Craft magazine. As mentioned many times in the past, I post these online for the benefit of hobbyists looking for information to assist in repairing or restoring vintage communication equipment.
*Only an indication possible. Readings will change materially regardless of type of power supply. Volume control full on, tuning control set for 550 kc., and the antenna outside of set. Use a meter of 1,000-ohms-per-volt type.
Excessive heat may injure the set; do not place it on a radiator or against a wall.
The models 20A and 25A vary only in the cabinet design. Regardless of the length of antenna used, do not leave any of the antenna wire curled inside the set as this may cause circuit oscillation. To operate the set on a 220 V. line use a limiting resistor in the line. On 32 V. systems use three 45 V. "B" batteries, a 32 V. limiting resistor, and a separate attachment plug; the regular power cord is not used. For 6 V. operation only the three "B" batteries, and an adapter cable and plug are required.
Radio Service Data Sheets
These schematics, tuning instructions, and other data are reproduced from my collection of vintage radio and electronics magazines. As back in the era, similar schematic and service info was available for purchase from sources such as SAMS Photofacts, but these printings were a no-cost bonus for readers. There are 185 Radio Service Data Sheets as of April 12, 2017.