1996 - 2016
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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June 1930 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.
The Model 81 chassis is fused at three amperes. The "antenna compensating control" is the 10-plate variable condenser marked CIA; while while the remaining trimming condensers are adjustable, through the shield can, with a screwdriver. Binding posts at the rear of the chassis permit selection of the correct tap on the antenna input inductance L1 , for the required degree of selectivity and sensitivity. When the tube is renewed at V4, it will probably be necessary to readjust the setting of R8. If circuit oscillation should appear in the receiver, it may usually be traced to a defective '24 tube, which should be replaced. The cord which operates the tuning dial is kept in tension by an adjustment which compensates for stretching; this is regulated by putting a screwdriver through a hole cut in the edge of the dial drum. Each of the R. F. transformer primaries (Ll1, as well as P in L2, L3 and L4) consists of a winding of about 200 turns on a bobbin at the grid end of the secondary; it has a direct-current resistance of about 80 ohms.
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 156 Radio Service Data Sheets as of December 6, 2016.