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Kirt Blattenberger (KB3UON)

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More Sensitivity from Your Transistor Radio
January 1969 Electronics World

January 1969 Electronics World

January 1969 Electronics World Cover - RF Cafe  Table of Contents 

Wax nostalgic about and learn from the history of early electronics. See articles from Electronics World, published May 1959 - December 1971. All copyrights hereby acknowledged.

Magnavox Model 789 AM / FM / Shortwave Radio - RF CafeWhere else on the Internet other than RF Cafe can you go for a daily helping of electronics-related material that ranges from the very beginnings of our chosen vocation through to the latest leading edge developments? That Q is rhetorical of course - and self-serving to boot ;-)  This handy-dandy trick for enhancing the signal on your AM radio appeared in a 1969 issue of Electronics World magazine. I remember doing this magnet "tuning" technique on my small, el cheapo pocket transistor radio that I carried with me when wiring houses and buildings while working as an electrician many moons ago after high school. It often made the difference between being able to listen to my preferred Top 40 AM station (combo top and music at the time) in Annapolis, Maryland - WNAV - and having to settle for Public Radio concerts. The "NAV" part of WNAV probably derives from "naval" both due to the U.S. Naval Academy being there and the fact that the entire Annapolis area is very water-centric, being located on the Chesapeake Bay and multiple surrounding tributaries. I do not miss the long, hot, extremely humid summers of boyhood. BTW, since I still listen to AM radio part of the day, I grabbed a magnet and ran it along the area where the internal AM ferrite rod antenna is located in my 1970s vintage Magnavox Model 789 AM / FM / Shortwave radio (it was Melanie's when she was a teenager) and sure enough, I was able to locate a peak in reception. Incredibly, I am able to use it daily to listen to WJR out of Detroit, which is 150 miles away in a straight line across Lake Erie. Here's an article showing how to repair a broken ferrite rod.

More Sensitivity From Your Transistor Radio

Ferrite rod AM radio antenna inside my vintage Readers' Digest Model 800-XR stereo receiver - RF Cafe

Ferrite rod AM radio antenna inside my vintage Readers' Digest Model 800-XR stereo receiver.

By John E. Campbell

Have you ever wished that you could squeeze just a little bit more sensitivity from your transistorized AM broadcast receiver, especially on a single station? If so, a gentle wave of a magic wand may make your wish come true.

All you will need is a permanent magnet and your receiver. If the magnet has a fairly strong field you won't even need to open the case of your set. Just tune in the station you wish to "perk up" and make a slow pass with the magnet down the length of the built-in ferrite antenna rod. If you detect a rather sharp increase in volume anywhere along the line, slow down and find the peak. That's all there is to it. You can now either balance the magnet where it is, tape it in place, or obtain some small ceramic magnets and tie or glue them in position directly on the ferrite rod.

Suitable magnets are available from Radio Shack, Edmund Scientific Co., and many others, A more universal supplier may be your local hardware dealer who handles magnetic cabinet latches. Just about any magnet will do as long as the field is strong enough to saturate a small portion of the ferrite rod.



Posted August 30, 2023
(updated from original post on 6/23/2017)

Crane Aerospace Electronics Microwave Solutions: Space Qualified Passive Products

About RF Cafe

Kirt Blattenberger - RF Cafe Webmaster

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 tying up your telephone line, and a nice lady's voice announced "You've Got Mail" when a new message arrived...

Copyright  1996 - 2026

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

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