Radio Waves Podcast #247

So you’re stuck at home.

You don’t want to get COVID-19, nor do you want to be a carrier and give it to grandpa. But the weather is so darn nice … what to do, what to do? …

How about trying to DX radio stations?

DX? Distance. The idea is to see how far away you can pick up a radio station, and the perfect weather we have right now happens to be the perfect weather for DXing both AM and FM stations. You don’t need a special radio to do this, but there are various models that work better than others.

For AM radio, signals travel quite far at night. Without getting too technical, the signal bounces off the atmosphere at night, travels back to earth, bounces up again, and so forth until it lands in your radio. This doesn’t happen during the day because the energy of the sun tends to absorb the signals (program note: technical people – correct me if I’m wrong), so night time is the best time for AM DXing.

An interesting aspect of this is what is called “critical time,” a time in which the sun has gone down but it is still light enough that a station has not had to switch to its night-time power; often stations need to power down somewhat — or a lot, depending on the situation — to avoid interfering with other stations. During this critical period, you can often hear stations from quite far away because they are still at full power.

As I said, any radio can work. For AM you need to get it away from things that might interfere with the signal: dimmers, some LED lights, computers, cable boxes, cheap “wall wart” power supplies. If it runs on batteries, try taking it outside. Turn the radio different directions and tune up and down the dial. Most of the better AM radios have large ferrite antennas — something that looks like a long bar with wires wrapped around it, — something that is often lacking in modern radios. Sometimes they are inside the case as they are in the old GE SuperRadio line.If your radio has a terminal to connect an external antenna, generally speaking, the longer the better. Super long runs of wire can aid reception. Unfortunately, that is often impractical. So a compromise can be made: a large run or wire wrapped around a large spool. See one such design on my web page, at socalradiowaves.com/columns/am_antenna.html. This design gives a combination of length and direction, which can aid in the reception of distant signals.

FM is a bit different. It is a signal that travels in a straight line and can be blocked by hills. For FM, height is paramount, both from a transmission standpoint and a reception standpoint. That’s why so many of the Los Angeles radio and television stations use Mount Wilson as their transmitter sites and why your roof antenna — if you still have one — works so much better than an indoor antenna.

Weather also plays a part: generally speaking, the better and clearer the weather the better the reception. However, that clear weather can also be a curse … sometimes distant stations can come in so clearly they interfere with local stations and both have reception issues. Sometimes multiple signals from different cities can hit at the same time and spoil reception as well. So the best way to do FM, if you are able, is to have a roof-mounted antenna that you can turn, or a really good indoor antenna that is directional and movable.

Some of the better FM tuners (and AM for that matter) have selectable sensitivity. Some recent tuners, including those from Sangean designed for HD radio reception, have FM sections that are quite good. But any radio can be tried.

I have to admit it has been years since I actively DXd … the dates on my list are 1980 and ’81. But the AM stations I was able to tune from my home near San Pedro back then include KBOI/Boise, Idaho, KTAR/Phoenix, KOA/Denver, the late-great KFRC/San Francisco, and KSL from somewhere in Utah. My prizes, though, were WLS/Chicago and WCCO/Minneapolis-St. Paul.

I never did much FM DXing, but in regular listening was often able to pick up stations from San Diego and Mexico quite easily, due in part to the signal traveling up the Pacific Ocean undisturbed. What was fun to get, though, were the stations from Santa Barbara and beyond, rare though they were due to my location blocked somewhat by a hill. I think FM DXing from my car was actually more successful!

A new twist on DXing, both on AM and FM, is the ability to detect and decode HD signals when a station broadcasts the system. For a time I was able to get KCBS/San Francisco in AM HD for very small periods, just a few seconds perhaps. But the radio — a Sangean tuner — was at least able to detect the signal was there. On FM, I can get KGB/San Diego’s HD signal often, but the old KFMB — which just changed call letters to the absolutely dreadful KFBG — rarely gets its HD signal locked. At least where I live.

The only problem with DXing these days, especially on AM, is the lack of anything you’d actually want to hear. But it can still be fun. If you try it, let me know how far you were able to pick anything up. At least it’s a diversion from the virus!