By: Mark Durenberger

Part 2, 2/18/98.

In Astronomy it's called a "Messier Marathon". It's a "star party", where folks gather to identify Messier-catalogued stellar objects. Ham Radio operators call it "Field Day", with the emphasis on the number of contacts. This story is about "Medium-Wave DX-ing" and the folks who log AM broadcast stations considered out of reach of normal receivers.

DX-Peditions are appealing to this long-time broadcaster because they provide the occasional opportunity to escape the urban interference, to a quiet location where we set up listening gear in search of elusive AM stations. With the increased band-clutter the FCC has wrought, this has become an increasingly challenging task. But the fun of finding a long-forgotten AM signal in the night-time ether makes it worthwhile.

Veteran R-W readers will recall my love affair with the romance of nighttime AM radio. There's a sense of community in barreling down the Interstate, keeping company with untold thousands of others who are listening to the same Grand Old Opry or truckers' show from Nashville, on an AM signal booming through the night and riding that long lazy skywave. I had forgotten how much fun this could be until I heard about the DX Audio Service from the National Radio Club (NRC), and when I "re-discovered" a hobby which has actually been around since the early 1920's! What follows is meant to update you on the changes in this age-old past-time and to inform you of some DXing resources, against the occasion when you too may wish to re-ignite an interest in this fun part of AM.

The DX Audio Service is a monthly audio magazine enjoying popularity among those interested in AM.

Anchored from Lima Ohio by veteran broadcaster Fred Vobbe, it's composed as a labor of love by Fred, Jim Snowbarger, Jerry Starr, Phil Wayne, John Bowker, Bruce Conti and listener-contributors. The tapes contain information on AM station assignments, station audio and profiles. Periodically, the DXAS produces "After Dark", a compendium of long-form programming, airchecks and interviews. You may hear a 1941 story on the "New WABC transmitter site on Columbia Island" or an interview on why the Voice of America shut down its Bethany Ohio Relay Station. Information on the DX Audio Service is available by writing Box 5031, Lima Ohio 45802-5031. Look for the NRC Web site or E-mail "".

You'll also find an extraordinary amount of information for the experimenter, published as reprints by the NRC, by the International Radio Club of America (IRCA) and by England's Medium Wave Circle. Look for newsletters and articles with solid theory and practical advice on technical topics from MW Propagation to antenna design. You'll learn of the work of dozens of DX-ers who share their experiences and the work they've done in designing gear for the hobby.

As just one example, one of DX-er Mark Connelly's great interests is using antenna phasing systems. Over the years Mark has probably built a half-dozen such phasors and publishes his work.

You can order reprints from the NRC Publications Center: P.O. Box 164, Mannsville NY, 13661-0164. Contact the IRCA at PO Box 1831, Perris CA 92572-1831.

Another example of a great source of information is an e-mail letter called "AM DX Newsflash", posted by Phil Bytheway. To receive this e-mail newsletter, send your e-mail ID to "".

To get your feet wet in this hobby, we suggest you borrow or buy a medium-price, high-quality portable such as a Sony IC-2010. Then look for the toys which take you beyond simple listening to make this hobby good clean fun. One of the best resources is Kiwa Electronics in Yakima Washington. Kiwa accessories include IF filters and very slick amplified loop antennas. You can add a "Regeneration Module" to a loop, to make a humdrum receiver really sit up and make noise. If you've never tried a good loop, you'll be pleasantly astonished! Kiwa can be found at "" or at 612 South 14th Avenue, Yakima, Washington, 98902.

Once you have a properly-accessorized receiver in hand, the only other thing you'll need will be some warm clothes against the dark night and, hopefully, a friend or two to share the fun. But don't make the initial foray any more rigorous than necessary, or you could be turned off at the start. Begin by reaching for the 50-kilowatters. You'll find target information in Funkenhauser's WHAMLOG page on the Internet or in the Broadcasting/Cable Yearbook. And NRC publishes a useful "Night Pattern Book".

So you say: "what's the big deal? I tune to 650 and there's Nashville". But bear in mind a lot of new stations have been authorized on 650 and the other Clears. WSM may still be a slam-dunk where you live, but there are other 650s to copy as well. The challenge is using antenna-orientation and nulling tricks to minimize the expected signals, reaching for what's underneath them. That's where the fun tools come in, and that's where this hobby becomes one part Fun, one part Art and one part Science.

The Science can be in understanding Propagation trends and predicting Post-Sunset/Pre-Sunrise catches. Or it may be learning to use a tuned loop, an "active whip" or a seriously-directional long wire, such as a "Beverage" antenna. These work great, but they may haul in 10 stations on the frequency. Apply the Science again; roll out a phasor. Phasing works on the principle of Common-Mode Rejection. Two antennas are combined so that common signals which appear in BOTH antennas are nulled out and what's left is the energy which hits only one of the antennas.

The "Art" to the hobby is in judicious placement of the antennas, so that the desired station comes into only one antenna. Phasing units are commercially available, or you can roll your own, using parts from the junkbox and guided by the available construction info from folks like Mark Connelly. I built one phasor out of old parts from a 1930's-era WCCO transmitter. A bit of overkill…unless you need receive equipment that'll handle 50 kilowatts!

While this hobby cuts across all ages, there seem to be a lot of folks like myself rediscovering nighttime DX-ing. We've been part of the early days of FM and we have one foot in tomorrow, but we may not be terribly excited about today's radio. Maybe we're listening because we're romantics at heart, or because we know that someday it may all be digital. When that day comes, who knows what'll happen to those lazy skywave fades? That magic nighttime AM sound may be lost forever.

There's a lot more to this story and the resources available, and if you're interested we'll be back with more detail. Meanwhile, give it a try. But I'm warning you. If you get bit by the DX bug, there's only one cure. That's buying better and better receive equipment!

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