FM DX ing!

[KB3HEY]

OK! I am new to this FM DX ing thing. I have tuned around on the truck radio (Chevy S-10) for awhile and see how I can get stations from Maryland, Delaware and Jersey. But what exactly am I looking for when"tropo" and "E's" start. I read on some of these message boards and some people are getting these long haul catches. I relize they may not be here in central PA but still.

Sorry for the stupid question.


Bob

 

[fussbudget]

Welcome to FM DXing! You are listening at the right time of year. From now until hopefully mid-July and again for a brief period in December, you may be able to pull in stations from 1,000 miles away or more. From late April till August, E-Skip is fairly common in the Northern Hemisphere. On a good day, it will "build" through Channel 2-6 on TV and spill into the FM band. Beginning at 87.75 on the FM dial, you may hear the audio from a TV Channel 6 far out of your normal "listening area." If the opening is strong enough, signals from FM stations up to and beyond 1,000 miles can be heard, especially on frequencies that are not in use in your area. Sometimes these signals are strong enough to "sound" local but with occassional fading. An opening can last from just minutes to hours. Listen for accents and/or languages not commonly spoken on your area radio stations. Listen for the names/locations of unfamilar sponsors that provide clues as to the station's location. Tropo is a little more common, especially in the Spring and Fall but the signals typically don't travel as far as during an E-skip opening. DXing can be great fun but your neighbors may wonder why you are spending so much time in your truck!

 

[dxer2_2000]

Also, if you are serious about getting into FM DX, it is advisable to invest in a good high end FM tuner & outdoor FM antenna to achieve the sort of results you read about from other DXers.

Pioneer tuners from the 80s are generally better than other brands without any modifications. Yamaha & Onkyo are also good. High end tuners would be more a necessity in your country (USA) as I imagine the FM band is very crowded over there & you'd need a tuner with good selectivity (to hear stations between your local FM stations).

Another option would be to jerry-rig a car stereo for "in-house" use. Mounted in a box & using a 12 volt power pack.


Most of all...Have fun!

dxer2_2000

 

[adamgre]

I remember about 15 years ago....I got a few stations from Tampa, FL and I live iin Toronto....It would be impossible to get stations from far places as the FM dial is more crowded.

 

[rbrucecarter5]

But what exactly am I looking for when"tropo" and "E's" start.

Timing for tropo is early morning and very late evening, spring into early fall. There is a definite, but unpredictable start date in March / April where I live, tropos are really strong and slowly diminish over the season. Sometimes, approaching weather systems enhance or cancel the tropo effect.

Sporadic E ranges from late morning to early evening, peaking in the hottest daylight hours. It is almost completely unpredictable, although sunspot activity can enhance it. Look for hot, dry conditions in a desert or hot, steamy over water halfway between yourself and the target - sometimes you can get lucky and the sporadic E will be there to an extent. Or it will create a more stable tropo - a good example is two way reception between Florida and the Gulf Coast of Texas.

 

[KB3HEY]

Just want to say thanks to all who gave me some food for thought about FM DX ing! Now I just have to go out and try it! Thanks again!

Bob

 

[Lawppy]

One other thing you can do is leave your radio on an open frequency in your area and just hear the signals that fade in and out.

For example.. In Coldwater, MI, where I live, I can have my car stereo tuned to 97.1 and hear all of the following stations at any given time.

WKRK Detroit, MI- 100 miles
WLHK Shelbyville, IN- 160 miles
WBNS Columbus, OH- 170 miles

These stations will always take turns fading in and then fading back into the static, usually lasting no more than one minute a piece.

 

[Grrrradio]

Sorry to hijack the thread, but Lawppy's idea of just leaving your stereo on a given frequency planted another idea in my head...

For a moment, I entertained a similar idea with respect to 87.9... which seems to be the channel of choice for various low-powered modulators (to relay XM, Sirius, iPods, etc.) I'd heard stories of 100-watt community stations and 50-watt translators occasionally making tropo and e-skip hops (though I've never been lucky enough to experience it myself), and those got me to wondering whether there's any rock-bottom minimum power to get a signal up into a tropo duct, or at the very least some interdependency between the power level and the likelihood of the signal doing anything DX-wise.

Presumably, the little store-bought modulators would be out of the question, even on a frequency like 87.9 that's free of high-powered stations... because they can only go 100 or 120 feet in ANY direction, including skyward, before becoming undetectable on a receiver. (The one I purchased specced its current consumption on the box... which, in combination with the battery voltage and a circuit efficiency estimate, allowed me to calculate its output power as being around 18 milliwatts.) BUT... three questions remain...

1) Do there exist any tropo-like conditions that may affect propagation on an extremely localized level... e.g. that might cut down on environmental path loss, or even create "mini-ducts" in air much nearer the ground, so that a low-powered modulator might throw a detectable signal for 300' instead of the usual 100'? (Related thought -- in the wonderful world o' physics theory, radio signals are supposed to follow the inverse-square law, but to what degree is that observed in reality? Let's say the signal from your modulator becomes functionally undetectable on a car receiver at 30 dBu or so... meaning that arithmetically, it's still about 32 times as strong as the one-microvolt standard comparison signal. Would this weak, noise-floor kind of signal actually travel 5.6 times as far as the signal your receiver can detect? And if so, might you see the occasional day where even a locally originated 0 dBu signal becomes detectable, allowing the modulator signals to come in, say, 600 feet away?)

and, of more practical interest, 2) If someone who bore a striking resemblance to Grrrradio decided to jerry-rig a Ramsey to run a watt out of his car's cigarette lighter, and use THAT to modulate his iPod on 87.9... would there be ANY chance whatsoever of that 1-watt signal making it through a tropo duct or even getting e-skipped over to, say, Texarkana from Minneapolis? ;D

 

[rbrucecarter5]

There seems to be a minimum power level required to make it up into the upper atmosphere and back down again. You could be talking about 20 miles round trip, not counting the duct itself which seems to be essentially lossless.

Tropos - I was 110 miles from Lubbock. Tropos were common and very strong, often pegging the meter on my radio. Lubbock stations were 50kW, 100kW. At the time, though, there was a ten watt college station and a 5 watt high school station up there. When the tropos pegged the meter on my radio, the college station was barely listenable. I never got the high school station. So the threshold on that was about 5 to 10 W.

As far as sporadic E - I have never had one on a low power station. The fade intervals are so fast any reception is probably fleeting enough not to be useful. It is not like tropos, which many people in rural areas rely on for entertainment. Before you go to work, reception is dependable. Late evening, dependable again - even if the station is gone during the day. Sporadic E - only DX'ers probably listen.

 

[dxer2_2000]

I've had 300 milliwatt stations via E-Skip at 2000km. These are tourist stations in NZ. I even got an ID out of one in Christchurch on 88.2.

dxer2_2000