DX'ing is a radio term for looking for radio signals from far away. AM broadcast DX'ing is the hobby of trying to "catch" as many far away AM radio stations as you can. AM broadcast signals by nature can carry for hundreds, if not thousands of miles at night. Radio hobbyist have been DX'ing since radio was first invented over 100 years ago. Many DX'ers keep journals of all the stations they have heard.
This is probably the most rewarding low dollar radio related hobby there is. The stuff you need to get started is probably already in your home. Even if you have none of the items required, you can pick up everything you need to get started for under $10 at the local thrift store. How's that for low buck hobby?
You might be saying...
"I can listen to whatever I want on the internet."
Yes you can. Listening to far away stations via radio though requires skill, some understanding of radio waves, luck, and no dependency on a middle man (the internet). It's just you and the broadcaster with nothing but air between the two of you.
Step 1: What You'll Need to Get Started.
Stick with a radio made by a well known manufacturer like Sony, Panasonic, or GE. There are hundreds of brands out there. If you're not familiar with what to look for, sticking with a well known brand gives a decent starting point. With the vast influx of cheap Chinese radios, there's plenty of brands to choose from but there's also lots of junk out there.
Look for an analog AM/FM only radio that doesn't have bluetooth, a memory card slot, or a clock. These modern conveniences come with a CPU (computer chip) that generates noise and can degrade the sensitivity of the AM portion of the radio. When it comes to entry level, simpler is better. The only feature you need is a headphone jack.
Why no digital tuning?
More on that later.
Step 2: What We're Listening for and Why It Happens.
Radio waves can bounce off the atmosphere or they can follow the ground. At night, AM broadcast signals will bounce off the atmosphere and back down to earth. This is a called a "hop" or "skip". It's possible to have multiple hops.
Wet ground or proximity to a body of water can help pull in signals. The reason for this is that the earth essentially carries one half of the signal. AM broadcast stations have very elaborate electrical grounding systems for this reason.
The weather can affect your DX catches. Rain and cold fronts can bring in signals you normally wouldn't pickup. Cold fronts in particular can cause a big increase in DX not only on the AM band, but also in the FM band.
Your AM radio will be directional. This means that it will pick up stations better when it's pointed a certain way towards the signal. You will figure this out by trial and error. Tune something in that's somewhat weak. Lay the radio flat on its back and slowly rotate the entire radio. Listen to the signal. You will hear the signal strength vary as you point the radio in different directions. This technique is handy when you have two or more stations on the same frequency and they are mixing together.
Step 3: Your Ears, the Most Important Tool in DX'ing.
Some things can only be learned by experience. Being able to identify a radio signal from faraway is one of those skills. What you're listening for is as follows..
1) Weak stations.
2) Stations playing music not popular in your area or ads for businesses you've never heard of.
3) Signals that fade in and out or waver in strength.
All radio stations have a call sign. The call sign is to a radio station what a license plate is to a car. It's unique to each station and identifies it. All legitimate radio stations identify with their call sign on a regular basis. This interim can be every 10-15 minutes or so. The call sign is 3 or 4 letters. Any broadcast station in the USA will have a 3 or 4 letter call sign that begins with either K or W. Examples of call signs are WOR, KDKA, and WIOD. If you listen long enough you will hear a station I.D. and possibly even say what city they cover.
Looking up a radio station's call sign can also tell you were it is. A good resource to use to look them up is the radio locator website.
AM radio is noisy. Do not expect it to sound like FM radio. Hiss, crackles, whistling, and sometimes picking up multiple stations on the same frequency are the norm. Your brain is the most important tool here. With practice you'll learn to hear things through the noise that casual listeners may miss. With enough practice you'll even be able to tell if a station may be coming in on skip just by the way the signal wavers. While there are very fancy radios with extensive features on the market, nothing beats a trained ear!
Step 4: Where to Listen and Dealing With Noise Sources.
Man made noise is your worst enemy. Lithium battery chargers like those used for almost all pocket sized electronic devices are nasty noise producers on the AM band. I have had some that wiped out all AM listening in the entire house! Battery charger noise will be characterized by a harsh buzzing sound that appears in between stations or can even cover up all the stations on the AM dial. Charger noise can carry for 100ft or more from the source. If in doubt, unplug any suspect chargers and see if the noise goes away.
Plasma TV's can also cause a harsh buzzing noise on the AM band, hence why going outside to do your DX'ing is a good idea.
Finally power lines can cause noise on the AM band. If you hear loud crackling noises all over the AM band after a rain storm or on humid nights, you may have a failing power line insulator up on a pole in your neighborhood. What's happening is that there is an actual arc of electricity jumping across an insulator somewhere. Sometimes you can even spot it at night if your lucky. If you do see the arc call it in. Some utility companies will come out and fix the insulator because it's causing them wasted electricity.
Step 5: Beyond the Basics, Vintage Transistor Radios of the 50's-60's.
For an AM broadcast radio, you really don't need more than 8 transistors to have a very good performing unit. Since there is such a low electronics part count in these old radios, battery life is measured in months or even years. It's not uncommon to find vintage radios with some form of damage from battery leakage. The batteries can last long enough that people forget to check them for leakage until it's too late.
Vintage radios will require some restoration. There isn't too much to do on basic sets but some work will still need to be done on radios that are found in all original condition. If you wish to learn about doing basic restorations on transistor sets, see my instructables on vintage transistor radios.
What to look for in a vintage transistor radio..
1) 7 transistors or more. Just like megapixels are a selling point today, transistor count was a selling point in vintage transistor radios. Ideally, you want 8 transistors or more but some 7 transistor radios perform quite well. Avoid vintage radios with less than 7 transistors. Transistor count on early sets is directly tied to performance.
2) A restored radio is a good idea for a novice. Transistor radio restoration is not very hard but requires electronics and soldering experience. Restored radios can be found on the numerous vintage radio boards on the web.
3) A standard headphone jack. Some radios used oddball sizes.
4) Standard batteries. Some early shirt pocket radios used oddball mercury batteries that are no longer made.
5) Vernier tuning. This is a form of gear reduction on the tuning that makes tweaking in weak stations much easier.
6) A large ferrite bar antenna. A radio is only as good as it's antenna. On an AM radio, the antenna is usually a black rod with coils of wire on it. The bigger the bar, the better it works.
What's in the pics?
pic 1 - Zenith Royal 1000 Transoceanic, my personal favorite vintage transistor radio.
pic 2 - Zenith Royal 3000 Transoceanic, GE, and RCA portables.
pic 3 - GE P780 portable. In many enthusiast's opinion, one of the best vintage AM transistor sets made.
pic 4 - Olympic 447 portable. This is a very early portable and only has 4 transistors. Not ideal for DX'ing.
pic 5 - Zenith 820 AM/FM portable. I have used this radio to pick up AM DX from multiple states. It's a good performer.
pic 6 - Zenith 820 inside showing ferrite antenna (black rod at top of radio with wires running to it).
Zenith by far produced more quality radios than any other American brand. Many models featured a hand wired steel chassis while other companies quickly ditched hand wiring in favor of circuit boards. My personal recommendation if you want to purchase a vintage transistor set that won't break the bank but works well is look for a Zenith that's been restored.
Step 6: Beyond the Basics, Entry Level Portables of the 60's - Today.
Something else that changed is transistor counts became less relevant. Transistors were expensive early on but by the early 60's, their prices dropped drastically. Less scrupulous companies stuffed transistors in radios just to make their products look good but they didn't exactly perform any better.
Radios from the 60's will need some restoration. Radios from the 70's are getting up there and may also benefit from an electrical refreshing. Sets from the 80's and newer should be ok.
Something else that will become apparent is that AM only radios were common up until about the early 70's. From the 70's onward you'll find most radios will be at least AM/FM.
What to look for?
1) A big ferrite bar antenna inside.
2) Vernier tuning or a large tuning knob.
3) A standard sized earphone jack.
4) Clean battery compartment free of corrosion.
5) A name brand you recognize.
6) If the radio is encased in leather or pleather as many 70's radio were, check that it's case is intact.
7) Pass on anything that mentions "boys radio" or "junior". These were sold as toys for kids and have very low transistor counts.
What's in the pics...
pic 1 - Radios similar to this 1960's Juliette where sold by the millions under many brands. They are characterized by a vertical layout with a handle up top, a pleather case, and some usually cheesy way of bragging about all the bands it covers. These will cover not only AM, but also a multitude of other bands. They are cheaply made. It's better than nothing but not the best choice for DX'ing. Be careful with the battery holders on these as they are often brittle.
pic 2 - Another 60's Juliette but this time AM only.
pic 3 - An early 80's Panasonic AM/FM and 8 track portable.
pic 4 - GE Super Radio series. These are considered an excellent modern day AM DX radio.
pic 5 - Eton crank emergency radio. These are very common and a good representative of a modern day analog radio.
My recommendation on an outstanding performing modern day radio that wont break the bank? The GE Super Radio series. These are excellent for AM DX'ing and can be found for about $30-50 on the used market.
Step 7: Beyond the Basics, High End Modern Radios.
CCrane and Eton (formerly Grundig) both offer some very nice radios albeit at premium prices. Expect to pay $150+ for a decent AM/FM radio from either company. You can easily spend much more for one of their premium models. A step up from this price point is a communications grade receiver such as an Icom R75. These radios will all cover not just AM broadcast, but a multitude of bands.
What's in the pics?
pic 1 - CCrane Radio SW
pic 2 - Grundig Satellit 750
pic 3 - Icom R75 communications receiver
Do you need one of these? Personally I don't think so. I owned a Grundig Millenium and own an R75. I have more fun hunting for DX on a basic radio I restored myself.
Step 8: Beyond the Basics, Digital or Analog Tuning?
Digital tuning pros...
1) Exact frequency readout.
2) Some radios have ability to store frequencies in memories.
3) May have up/down buttons which some folks prefer.
Digital tuning cons...
1) Only the better radios will offer very small tuning steps.
2) Radio will have a CPU and a digital display which means shorter battery life than basic vintage set.
3) Radio will have a CPU. Cheaper sets will be lacking in proper internal shielding. The processor inside that drives the digital tuning can be a source of noise when trying to listen to distant stations.
Analog tuning pros...
1) No CPU needed. Radio can have much longer battery life.
2) No tuning steps. The ability to fine tune and zero in on one station when two or more are on the same frequency can sometimes be made easier by analog tuning.
3) There is always a tuning knob which many folks prefer when DX'ing.
Analog tuning cons...
1) No memories on portables.
2) Tuning scale is rarely accurate on portables.
My personal preference?
I like analog tuned radios for DX'ing. The ability to rock the tuning control back and forth to zero in on a very weak signal is very important to me. This can be done with some of the better digitally tuned portables with adjustable tuning steps but I just prefer the analog dial.
Step 9: You NEED Headphones!
When listening to music, one can hear details they never heard before using headphones. This also applies to DX'ing on the radio. Headphones or earbuds will help block out outside noise and let you concentrate on the radio signals.
Can you DX with just the speaker in the radio?
Absolutely but why strain and miss out on the very weak stations? With the proliferation of portable MP3 players, it seems everybody has a set or two of earbuds laying around.
What to use?
You have many choices ranging from vintage radio headphones to modern MP3 player earbuds. The basic choices available to you are pictured below.
pic 1 - A genuine antique set of earphones. These are cool looking but very uncomfortable as they squeeze your head. They will also need to be fitted with a proper connector to work with your radio.
pic 2 - Modern full size headphones. No need for Dr Dre Beats here. Whatever fits comfortably will work as long as its not too bassy. Make sure it's got a plug compatible with your radio.
pic 3 - Modern earbuds.
pic 4 - Vintage crystal type earphone. This style is ideal if you want portability and an audio response that's best tailored for AM radio DX'ing. By design, these crystal earphones don't reproduce low bass which is distracting when DX'ing. These can be found new. Make sure it's got a plug that fits your radio.
Stereo Vs. mono...
AM is mono. Not all AM radios had jacks that would work properly with stereo headphones. Worst case scenario is you end up with audio on only one side of a stereo headphone. No harm, no foul. It wont hurt anything but if it drives you nuts, they do sell mono headphones or you can wire in your own mono plug on your headphone cable.
Step 10: Any Other Tricks to Improve Reception?
On radios with a ferrite bar antenna, you can use a coil antenna booster such as the one in pics 1 and 2. These are manually tuned so it makes tuning for DX a bit more involved. You have to tune the radio and at the same time turn the knob on the antenna to "follow" the radio along the band. It makes for a bit of work but one can get the hang of it with some practice. These antennas are really better suited for boosting the signal of a weak station you already found than trying to cruise the dial with it.
A second option for some is connecting the chassis of your radio to a good ground. If you have a spot outdoors you sit at and do most of your listening, hammer down a ground rod and run a wire from it to a clip. you clip the ground wire to the chassis of your radio when you go out to DX hunt. It helps but only in places with humid soil. Be careful whenever you hammer down a ground rod as there may be underground pipes or cabling. Make sure the ground rod area is clear of utilities.
Yet another option is run a wire to a chain link fence if you have one and put a clip on it so it can be clipped to the chassis of the radio.
Step 11: Hey This Is Cool! I Want to Learn More About Radio!
Even if you don't have an interest in becoming an amateur radio operator, the local ham radio guys are a good source of info on radio related topics. To find out if there's any amateur radio clubs in your area, just take a look on the American Radio Relay League's website www.arrl.org and search for clubs.
What's in the pic?
That is the Dade Radio Club of Miami operating a ham radio station at a park as part of a public service event.
I hope you found this instructable on AM DX'ing interesting and useful. Drag out that AM radio and have some fun hunting AM broadcast DX!