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In the Winter time AM radio waves travel much farther. This draws many of us into the long-distance AM radio listening hobby BCB-DX. To those getting started just figuring out what all the odd noises are is half the fun.

Tick Tock

Nighttime reveals several channels on the AM broadcast band with an odd clock-like ticking sound. Well, it really is a clock sound. The ticking and tocking is accompanied by a period Morse code broadcast of two letter R’s. The source of this is the island of Cuba and the radio stations call themselves Radio Reloj or Radio Clock. Listening carefully you also hear a non-stop Spanish language broadcast under the clock. On the east coast of the United States especially, Cuba’s radio stations are often louder than our own. When WTNT, 570 KHz lowers its power at night Radio Reloj often booms in. Radio Reloj has numerous locations in Cuba and broadcasts on several frequencies. Another clock can be heard at 950 KHz. Can you find them all?  Clue: Google: Radio Reloj.

The Steady Tone

It is called a heterodyne. Two stations (or a station and an interference signal) with carrier frequencies just a few KHz apart produce an audio frequency in your speaker  equal to the difference in frequency between the two stations. This is most noticeable when a European broadcast station beats against one in the United States. European stations use different center frequencies than do US stations to avoid direct interference with stations on our continent. Two American stations a few hundred hertz off frequency of each other will also produce a tone of just a few hundred hertz.

Yes it is possible to hear European broadcasters very clearly at times especially if you have a directional loop antenna connected to your AM radio. When you hear a heterodyne try zeroing in on the weaker station that is off the American channel by a few KHz. Leave your dial at that point and wait for a fade that brings the station in with a clear signal. In many cases the AM station here will have such a strong signal hearing the station will be very difficult unless you can minimize the strength of the stronger station with a directional loop.

Here are a few places to look. I logged carriers on frequencies in between our own stations. Some I have identified and others remain a mystery. An easy “tweener” is 555 KHz which is radio station ZIZ on the island of St. Kitts in the Caribbean.

567 KHz carrier next to 570 KHz WTNT

612 KHz carrier next to 600 KHz WCAO

693 KHz carrier next to 690 KHz CBU and 700 KHz WLW

765 KHz carrier next to 760 KHz WJR and 770 KHz WABC

895 KHz Voice of Nevis St Kitts and Nevis next to 990 KHz CHML, Radio Progresso in Cuba can be heard beating against WLS in Chicago at 890 KHz.

1314 KHz “NRK Prog 1″ in Norway next to 1320 KHz WJAS

Noise

Am radio is susceptible to noise from a variety of sources that are natural and man made. One of the more interesting are lighting storms. Lighting generates strong radio waves that can be heard across the AM band. It is an indicator that outside antennas should get disconnected immediately especially end-fed long wire antennas. One Summer evening I didn’t react fast enough and actually heard the sizzle-crack from the back of an ICOM R70 connected to an eighty foot end-fed wire. Two hundred dollars later after a trip to the ICOM service facility I could use my AM radio again.

Other sources of noise include motors, lights, ignition systems, power lines and the like. The ARRL web page has a link to a Radio Amateur that maintains a web page of sounds he has tracked down over the years.

Questions?

A number of PopularWireless readers enjoy BCB-DX. If you have a question feel free to ask here in the blog or visit our Forums. No question is a silly question especially when you are getting started in the hobby.