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Listen to Shortwave Broadcasts on an AM Radio

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Picture of Listen to Shortwave Broadcasts on an AM Radio
The larger radio is my Sangean ATS-803A shortwave receiver. The smaller radio in the foreground is a travel alarm/AM-FM radio from the late 1980s. I converted it to receive shortwave frequencies between 4 and 9 MHz and used it that way for a while. You can make a like conversion on an AM radio you own.

For those with a deeper interest: Once while vacationing in Oregon I heard a broadcast from Radio Australia about a radio operator on a naval ship who learned to recognize the "fist" or touch of wireless operators from other ships before he heard their call signs. When WW II was about to break out the German radiomen ceased using their call signs to hide the identity of their ships and their location, but he knew each one from his distinctive "fist" on the Morse code key. The radio signals also modulated in a distinctive way when a ship was transmitting from one particular area. Not only could he identify the German ships from the way the radiomen tapped out their Morse code, but he also knew exactly where some of the ships were located at the time. This is just an example of things you can hear on shortwave broadcasts.
 
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Step 1: Not as popular as before

Picture of Not as popular as before
Shortwave frequencies bounce off of the ionosphere and return to earth halfway around the world. It is easy to receive broadcasts from another continent; depending on conditions, time of day, signal strength, and target area for the broadcast.

Pictured is the Passport to World Band Radio. A new edition is published each year. It is a yellow pages guide to international broadcasts.

Unfortunately, shortwave broadcasts are not as available as a couple of decades ago. This is due to budget cuts and the Internet. Now you can download Podcasts from many national broadcasters. These Podcasts are in FM quality and without the static interferences associated with shortwave broadcasts. Still, there is a certain romance from listening to a radio signal from the other side of the globe.
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dmagryta1247 months ago

I did this project, with very rushed and very sloppy craftsmanship, and much to my surprise it works! I'm able to pick up only a few overlapping channels; a morse channel or CW beacon of some sort, and a very distant foreign channel. I just clipped the antenna wire to a wire basket, and the reception is just fine that way. Great instructable! Thanks!

Phil B (author)  dmagryta1247 months ago
I am glad it works for you. On the one hand, I miss the wide variety of things that were available on shortwave bands twenty years ago. But, on the other hand, I really like the crisp clear audio I can now download from the Internet and play anywhere, even in my car. Thank you for trying it.
sconner112 months ago

Do the new wraps need to be in the same direction around the ferrite as the original factory coil?

Do the new wraps extend the coil in a serial connection or parallel it?

Phil B (author)  sconner112 months ago
I paid no conscious attention to the direction of the windings relative to those already on the ferrite coil. The windings are in parallel.
Cambenora1 year ago

Cool project. I'm going to try this one. Thanks!

Phil B (author)  Cambenora1 year ago
I hope it works well for you.
oh ok thanks
what if your ferrite rod antenna is farther away from the variable capacitor and the 6 inches of wire wont reach it, can i just cut the magnet wire longer?
Six inches was only an approximate length for most radios. Go ahead and use a longer piece according to your needs.
This is brilliant. I have dug out my old Realistic DX-350 and started listening to SW. It is fascinating. If I did this to a AM radio for my kids to play with, would there be a way to make it switchable to preserve AM functionality or does the loose coil adversly effect the AM signal?
Phil B (author)  BigBadgers20012 years ago
I expect you could put a switch on the coil windings you add. Try disconnecting one leg to see if that works. If it does not, try disconnecting the other end of the coil and see if that works. Add a single pole or a double pole switch according to what you find.

You will need to help your kids understand tuning an SW station on a modified radio like this requires a lot of patience because a signal is just a blip on the dial.

I do not listen to much SW radio now because broadcasts I would want to hear are available now as Podcasts I can hear on my schedule in much better quality than I got with SW radio.

Thank you for your comment and for looking. I hope you and your kids find enjoyment and success in your efforts.
Chakazuluu3 years ago
Wow you brought back some memories. When I was in elementary school (I am 70 now) my father had an old stand up Philco Am and shortwave radio. I sandwiched a piece of aluminum foil between two pieces of card board with two screws connecting the two antennae wires and put it under the dial phone we had. It brought in some amazing frequencies.

I think I will do this with an old AM radio I have. Thanks for the memory.
Phil B (author)  Chakazuluu3 years ago
You are four years older than I am. We had a similar radio, but ours was a Zenith. For whatever reason, I do not remember ever getting a shortwave broadcast on ours. At the time I do not think I knew to attach an external antenna. I am guessing that what you did coupled with the telephone lines by capacitance to make use of them as an antenna.

Thank you for looking. I hope you are able to make your old AM radio receive some shortwave broadcasts. I think I may have mentioned it worked pretty easily on one radio, but not so easily on another radio I still have.

Shortwave has been a lot of fun. Regrettably, the band is not nearly as full in recent years, although at night I still hear a number of things in Spanish. Radio Havana broadcasts in English and there are some Christian broadcasters. I miss things like Radio Canada, Radio Austria, Radio Australia, etc. Thank you for looking.
Now that you mention it ours was a Zenith also I thought it was a Philco but when you mentioned Zenith suddenly the memory came back. I got the aluminum foil antennae idea from a short blurb in Science and Mechanics.
Phil B (author)  Chakazuluu3 years ago
If you go to this link, I think the radio shown is very close to the one we had, if not identical to it. Several details I remember correspond. I am not sure of other details.
Oh my goodness I can't believe this it is precisely the same radio we had. It is like you took me back in time and opened up a flood of memories that was seemingly forgotten. It is like a door to the past has been opened and I can see situations and occurrences clearly that was fuzzy and inconclusive. I need to ponder on this for a bit.
Miketan3233 years ago
Its weird, I'm picking up stations in the 10-15 kHz range. Hmmmmm...
Phil B (author)  Miketan3233 years ago
Good for you. It is working. You have shifted your radio's frequency range to the 10 to 15 MHz range. My experience with my radio was the 4 to 9 MHz range, as best I could tell. Perhaps it is a difference in radio circuitry.
Johenix4 years ago
Recognizing CW operators by 'FIST' dates back to the American Civil War (War of Northren Agression) when a Confederate telegrapher spotted the strange sending of a Union intercept tap operator and sent: "Get off the line you damn yankee!"
I have a huge digital Aiwa stereo on my living room, it can tune Am, FM and SW but I've never been interested on SW. Gonna attach its antenna and try to listen to it sometime. :)
charlieb0005 years ago
i have a car radio i bought ages ago but never installed. it is not PLL, but very simple. it has little coils soldered into the board near the tuning cap but no ferrite. it also has a few (maybe six) metal boxes with painted ferrite inside. how can i convert this? it would make an excellent reciever as the tuning knob is really geared down and takes 16-20 turns to go accross the band. i guess i can do it as instructed with some ferrite, but the tuning cap has six pins and i dont know which to join to it.
Phil B (author)  charlieb0005 years ago
I do not know enough about car radios to say if it is possible.  You can, however, order a shortwave converter for your car radio.  Here is one link.  But, it is not cheap--about $165. 
I found this i'ble just in time. I have an on-going project on pause so I think I'm gonna turn it into a shortwave radio to pick up my friend's Morse code.
Phil B (author)  nutsandbolts_645 years ago
It should do that for you.  This makes an interesting receiver.  But, it is not always a great receiver.  I hope it does what you need.
 If I can find it that is. 
I used to get SW stations back in 1991 with a cheap $20 radio, but the radio fell apart, but I have kept in touch with the world.   The radio was a portable Windsor TV/AM/FM/Weather radio.   I also had a friend that was picking up shortwave broadcasts on his AM/FM clock radio until I told him to put the ferrite rod back in place.   It was a new come back experience.    Now I feel I might experiment again.
Phil B (author)  gccradioscience5 years ago
Thank you for trying this modification and reporting back that it worked for you.  It makes a crude shortwave receiver without some of the circuit refinements in modern receivers, like spurious signal rejection and phase locked loop (PLL) controlled tuners.  Your friend's experience with the presence or absence of the ferrite rod on his clock radio is interesting.  The early 1990s was the height of my shortwave listening experiences.  The number of stations I am able to receive currently is only a shadow of what was available 20 years ago.  But, I now download Podcasts from some of those same stations and convert them to CDs I can play in my car.  My aim was to improve at understanding spoken German.  Although I miss the shortwave broadcasts, the audio quality on the Podcasts is far superior to anything I ever heard on shortwave.   (During the first Gulf War I once heard a news item on shortwave that did not make the news reports in the USA until two days later!)   
I tried it,  it works very good, except it drifts alot, it takes patience to tune and experimentation.  I also used one of my indoor shortwave radio antennas.    What a great way to get access to world band on a radio you do not use.  Great Job!  
static5 years ago
For whatever reason I was lead back to this instructable, so I thought I would search out and post some links for the noobs. I did find a schematic for the typical transistor radio here http://my.integritynet.com.au/purdic/am_rec.htm . Go here to find the link to part 2 it's in the left column as you scroll down the page. You can read the USN electricity and electronics train publications here http://www.tpub.com/content/neets/http://www.tpub.com/content/neets/ The documents can be downloaded free as well, but I can't find my bookmark for doing so. OK here it is, this will keep nerds busy for awhile.
static static5 years ago
Came back to get an url I failed to bookmark, and notice errors in my post, Exclamation deleted.

Read the USN training docs here http://www.tpub.com/neets/
Download them here http://www.tech-systems-labs.com/navy.htm
kmpres5 years ago
Very interesting indeed! I wonder if you can tell me how to do this with an FM radio. I live in Tokyo and would like to hear Tokyo FM broadcasts on my Bose Lifestyle 30 stereo(American band) but can't because the Japanese FM band is from 80 to 88 MHz and the American FM band is from 88 to 108 MHz.. Is there a way to adjust the band down in my stereo?
Phil B (author)  kmpres5 years ago
Perhaps some of those with a background in engineering or amateur radio can tell you. Shifting the FM background is way beyond my knowledge.
Mydnight Phil B5 years ago
Essentially, you can't. Frequency Modulation (FM) radios pick up signals which carry the data (audio) by shifting the frequency (number of cycles per second) of a carrier wave. Amplitude Modulation (AM) radios work by shifting the amplitude (amount of power) being pushed in to a carrier wave. Shortwave radios are just AM radios that operate on a different frequency range; however, FM radios work on an entirely different technology (If you were to graph it, AM radios measure vertical change and FM radios measure horizontal changes in the periodicity of a carrier wave (which, unmodulated, is a sin wave). /nerd mode off
kmpres Mydnight5 years ago
Quite right, thank you for that well thought out response. I can't help thinking, however, that the only difference between an American FM receiver and a Japanese one is a 10 to 20 MHz shift in carrier frequency. Is there a way to add, say, 10 MHz to an incoming Japanese FM signal and thus fake out the front end of an American FM receiver into thinking that it was getting a carrier within its designed range? You'd, in effect, fit the Japanese band inside the American band which is twice as wide. I imagine a kind of frequency adder circuit or "pre-tuner" would be necessary. There are easier ways to do this, not the least of which is to simply buy a Japanese tuner and use the AUX port, but why waste the chance to take apart a $2,000 stereo and with a handful of parts, make it work better than before? (This is the price of nerddom.....;-)
Mydnight kmpres5 years ago
Sorry, I misread your original post -- I thought you were talking about changing an AM radio to receive FM signals, or vice versa.

If your FM reciever circuit is relatively simple (a one-transistor type), you could probably achieve the result you want by swapping out two capacitors -- essentially, one determines the low end of the signal range and the other determines the "band spread" (i.e. sensitive range). Here's an article with diagrams showing what I mean:

http://www.vk2zay.net/article/129

I wouldn't want to recommend screwing around with it too much though -- if you swap the wrong caps, you run the risk of completely frying your (apparently very expensive) radio. I'd also like to add a caveat: Although I'm an amateur radio enthusiast (as of yet just theory, although I hope to get licensed soon), I have never built a radio more complicated than a simple crystal receiver, so I could be completely off base.
abadfart5 years ago
do you know how to convert from a 49 MHz radio to a 27-MHz radio?
static abadfart5 years ago
Actually there is no "ideal" with these kind of modifications. That means securing the mods is really advised, unless operating conditions warrant it. you may need to go back to adjusts the turn spacing ot even use another coil with more, maybe less turns
Phil B (author)  abadfart5 years ago
Back in the 1920s and 1930s there were plans for AM and SW radios you could build at home. Most of them had coils you could remove to plug in a different coil for receiving a different range of frequencies. There might be a coil you could remove or alter, but I would have no idea about specs for making the coil to replace it. Some radios, like scanners, use different crystals to select different frequencies.
could i possibly add a switch to the 7 turn coil to turn the SW off and go back to AM? the radio i have is an AM/FM is there a way to tell which side to connect to?
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Phil B (author)  mikemmcmeans5 years ago
To switch back to AM from SW you need to remove the seven turns of wire you added. Just disconnecting one of the leads did not eliminate SW reception and restore AM reception for me. Unfortunately, there is no way I can tell you to which tabs you will need to connect the ends of the wire for the extra coil. You can try to guess it out, but finally, it will be a matter of trial and error. And, there is the possibility it will not work on your radio.
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