Electronics World articles Popular Electronics articles QST articles Radio & TV News articles Radio-Craft articles Radio-Electronics articles Short Wave Craft articles Wireless World articles Google Search of RF Cafe website Sitemap Electronics Equations Mathematics Equations Equations physics Manufacturers & distributors Engineer Jobs LinkedIn Crosswords Engineering Humor Kirt's Cogitations RF Engineering Quizzes Notable Quotes App Notes Calculators Education Engineering magazine articles Engineering software Engineering smorgasbord RF Cafe Archives RF Cascade Workbook 2018 RF Symbols for Visio - Word Advertising RF Cafe Forums Magazine USAF Radr Shop Sponsor RF Cafe RF Electronics Symbols for Visio RF Electronics Symbols for Office Word RF Electronics Stencils for Visio Thank you for visiting RF Cafe!
Berkeley Nucleonics Academy RF Boot Camp - RF Cafe
TotalTemp Technologies (Thermal Platforms) - RF Cafe

About RF Cafe

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...

All trademarks, copyrights, patents, and other rights of ownership to images and text used on the RF Cafe website are hereby acknowledged.

My Hobby Website:


KR Electronics (RF Filters) - RF Cafe

Crosley Model AC-7 and AC-7C Radio Service Data Sheet
May 1930 Radio-Craft

May 1930 Radio-Craft

May 1930 Radio-Craft Cover - RF Cafe[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.

Have you ever heard of a Mershon condenser? Me neither, but this Crosley Model AC-7 radio used one (or more). Ohio State University alums are familiar with the name Mershon, if not the man. Ralph Mershon was, among other things, an early manufacturer of electrolytic capacitors. This 1930 service sheet for a Crosley radio mentions the propensity of Mershon capacitors to experience breakdown of the electrolyte when the radio is not used for many months. Rejuvenation is necessary via a prescribed procedure to ensure effective operation in removing the 60 Hz hum in the audio.

Crosley AC-7 and AC-7C

This receiver employs one (first) stage of tuned "push-pull" R.F., a second stage of R.F. amplification (in which circuit oscillation is pre-vented by a "losser " resistor R12 of 750 ohms and the reversed tickler winding T of L2), a regenerative detector, and the usual two stages of transformer-coupled A.F. amplification. The tubes used are as follows: V1, V2, V3, V4 and V5, X-'99s; V6, '12; V7, BH-type gaseous rectifier. (The specified tubes must be used.) The filaments of the amplifier and detector tubes are connected in parallel, and the filament current is obtained from the rectifier V7 and high-voltage winding S1 of the power transformer PT. The manner of obtaining grid bias for these tubes is indicated in the detail circuit.

Crosley AC-7 and AC-7C Radio Service Data Sheet, May 1930 Radio-Craft - RF Cafe

An insulating film on the plate of the Mershon condenser is built up at the factory; but this gradually breaks down if the receiver is not in use for some time. To build up a film on the plates the receiver is put into operation with all tubes in their respective sockets. At the start of the reconditioning process, resistor R16 should be turned to extreme left, and resistor R1 set mid-way. Operate the set for ten minutes to half an hour, noting the current reading on the milliammeter MA; the value for correct operation of the set is between 55 and 60 milliamps. As the current increases, R16 should be adjusted to maintain this reading, A greater length of time than fifteen minutes is seldom required before the set begins to play well. If C10-C11-C12 is defective, the Mershon unit should be replaced.



Posted September 21, 2016

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 227 Radio Service Data Sheets as of December 28, 2020.

Exodus Advanced Communications Best in Class RF Amplifier SSPAs
Anatech Electronics (RF Filters) - RF Cafe
Innovative Power Products Passive RF Products - RF Cafe

Please Support RF Cafe by purchasing my  ridiculously low−priced products, all of which I created.

These Are Available for Free