Monday, April 26, 2010
Cross Country Pipeline - A Daytime MW DX Tale
This is a story about daytime mediumwave DXing. To set up this story, let me tell you that I am on my way back to New York from Arizona, by way of Denver. As usual, I like to DX the mediumwaves on the way, often from my truck radio. There is little but routine DX until I leave Denver headed east on Monday morning, April 19th. Over the next two days I will have some new personal daytime MW DX distance records and an incredible DX experience to remember. And here is the story....
MONDAY, APRIL 19
Denver, Colorado. 0900L (9AM). I am headed due east out of Denver on I-70. I-70 snakes through Colorado, Kansas, Missouri, Illinois and onward for the eastward traveller, through the major cities of Kansas City and St. Louis, crossing the Mississippi River at St. Louis. Kansas itself is 425 road miles across and Missouri about 250. The eastern plains of Colorado and west-central Kansas are about as flat as a pool table, and there are basically no trees until you near Topeka, Kansas, closing in on Kansas City, some 625 road miles distant.
To add interest to the trip, I decide to see how far I can hear three prominent Denver stations: KHOW-630 (5KW), KKZN-760 (50KW), and KOA-850 (50KW). 760 KHz and 850 KHz are clear-channel frequencies. I am DXing on a 2006 Ford Ranger truck radio. The truck radio is adequately sensitive and uses a short whip antenna.
I cross the Colorado-Kansas state line, 160 miles out, about 1300L. All three Denver stations are still powering in, even lowly KHOW-630 at 5KW. No difference in strength can be discerned. Remember, it is daytime, and midday. The D-layer has long since "re-coagulated", and we are well outside the 2-1/2 hour guard zone around sunrise and sunset. It always amazes me why these extreme daytime MW DX distances are common out west, and I rarely see this happen in the east. My fellow Ham buddy Jeff, K3OHU, says it is due to all the clutter in between station and receiver that attenuates the signals. Out west are wide-open spaces. Perhaps he is right. I proceed on, as I plan on driving another 2-3 hours before stopping.
I pass Goodland, Colby, and Oakley, Kansas, closing in on 300 miles now. The three stations continue to hang in, very strong. I might expect that of KKZN-760 and KOA-850, both 50KW stations, but not of KHOW-630 at 5KW.
At 1530L, I pull into Hays, Kansas for the night, some 309 miles as the crow flies from Denver. KHOW-630 has weakened some, but is still of medium strength. KKZN-760 and KOA-850 are still powerhousing through the truck's speaker. Somewhere in the last hour I have crossed into the Central Time Zone, losing one hour. Tomorrow, Tuesday, should be interesting, and we shall see what and who shows up in the morning.
TUESDAY, APRIL 20
Hays, Kansas. I am up at 0530L and back on the road. It will still be dark for another hour. Intermittent low fog hugs the road, mile after mile. I take a scan around the band to see what's happening. Within fifteen minutes I hear all four sides of the country - the west coast: KFI-640 Los Angeles, CA, the east coast: WSB-750 Atlanta, GA, the northern border: WCCO-830 Minneapolis, MN, and the southern border: WWL-870 New Orleans, LA. Also heard before 0630L and daylight are WGN-720 Chicago, IL, WBAP-820 Dallas TX, KEEL-710 Shreveport, LA, and KOKC-1520 Oklahoma City, OK, all with strong signals. Things are about to get interesting.
East of Hays, Kansas, and still dark out, the three Denver stations are nowhere to be found, buried, I suppose, under the jumble of nighttime signals on their frequencies. It starts to get light, and I hurtle east across central Kansas, wondering if this will be the end of hearing daytime Denver DX for this trip, as I will soon be out of range.
Nearing Salina, Kansas, stations to the extreme east are fading away due to the impending sunrise. WSB-750 Atlanta fades, as does WGN-720 Chicago. Popping up on 720 KHz now is a strong signal out of 50KW blowtorch KDWN, Las Vegas, NV. KFI, Los Angeles, holds its own on 640 KHz. I tune to 740 KHz looking for KCBS in San Francisco, expecting something further up the west coast, but nothing. KGO-810, San Francisco, is also absent. Next I tune to 770 KHz - the channel was vacant just a little while ago - and now there is powerhouse KKOB in Albuquerque, NM. I have a quick breakfast in Salina at 0645L, then back on the road at 0730L.
East of Salina, Kansas, the sun is well up now. A pleasant surprise! Denver's KOA-850 is back in there, alone on frequency. KKZN-760 is in there too, but competing with KCCV-760 (6KW), a religious station in Overland Park, Kansas, near Kansas City. KHOW-630 has not showed.
I come to Topeka, Kansas at 1020L. The low fog is lifting. It is more than 2-1/2 hours past sunrise and into the daytime DXing timeframe now, and the nighttime skip has totally vanished. KHOW-630 has still not reappeared and I suspect we are out of range for it anyway. KCCV-760 in Overland Park has overtaken Denver's KKZN-760, I figure for good, as KCCV will only get stronger as I approach Kansas City. By then, presumably KKZN will be out of range. KOA-850 hangs in there quite nicely with a nice medium strength signal all by itself.
I roll through Kansas City, crossing the Missouri River, and on into the state of Missouri at 1135L. KOA-850 is still hanging strong. KKZN-760 is completely obliterated by the Overland Park station KCCV. I press onward for Columbia, Missouri, just past the center of the state, another 120 miles distant.
Fifty miles inside Missouri at 1220L, the Overland Park station fades, revealing Denver's KKZN-760 again, at a good signal strength. KOA-850 continues to hang fairly strong, still alone. Surprisingly, the signal strength of these two are still respectable through the truck's speaker, and arm-chair copy. KHOW-630 is still absent. I hear a weak religious station creeping in on 630 KHz, probably KJSL-630, St. Louis (5KW), nearly 200 miles in front of me. I am getting close to my personal daytime DX record of 675 miles. Ironically, that is held by KKZN-760. I have received it twice while in southwestern Arizona.
I pass through Columbia, central Missouri, at 1330L after stopping for a very quick lunch. The excitement is building, as I am now passing my daytime MW DX distance record mark of 675 miles, and I have two stations still in contention for a new record. I can hardly contain myself. To my amazement, Denver's KKZN-760 and KOA-850 are still hanging in with weak to medium signals, well above the noise level. The fades and peaks have become long and drawn out, perhaps 20 or 30 minutes between them, but even the fades are still readable. What gives? I have never heard MW DX signals at this strength at this extreme distance during the daytime. The Denver weather report on KOA indicated fog still on the ground in the Denver area at their 1130 AM local time. I start to wonder if the ground fog is part of this scenario?
A few minutes go by, then bad news. I start to hear splatter on KKZN's signal. The splattering station, at 770 KHz, is playing a sort of ethnic variety music, so I assume it must be coming from station WEW-770 (reportedly 10KW), located in St. Louis, Missouri. This can only get worse as I close in on St. Louis, and I fear that in time I will lose KKZN permanently to it. To make matters worse, underneath KOA-850 another station appears, gaining in strength. I can't identify it yet.
East of Columbia, and less than 100 miles from St. Louis and the Mississippi River, I decide to check for WSM-650, Nashville, Tennessee, the famous Grand Ole Opry station. This spring on my trip out it carried well into southern Missouri, down the I-44 corridor. I tune to 650 KHz. There I find a station, weak-to-medium, in the clear. I listen for ID, as the 1400L news is on but I missed the top-of-hour. They give the local weather report. Something about Wyoming and Cheyenne. What is this? No, it can't be! Then the ID comes. "This is KGAB, 650 AM, Cheyenne"!
I can't believe my ears. KGAB near Cheyenne, Wyoming transmits with a power of only 8.5 KW! But there it is with a perfectly listenable signal strength through the truck speaker at an amazing daytime distance of 710 miles! The local time is 1405 CDT, and an hour earlier at 1305 MDT in Wyoming. KGAB is totally in the clear, without side splatter or other interference on-frequency. The thought occurs to me that I'm only about 100 miles from the Mississippi River and the Illinois state line, and I begin to wonder if the two Denver stations and Cheyenne will hang in there long enough to get to the river. I race towards the Mississippi, as things are starting to deteriorate on all fronts.
The stations are getting weaker. Denver's KKZN-760 is getting hit very hard with 770 KHz splatter, and is almost unreadable now. KOA-850 is almost totally covered up with co-channel interference. I identify the offending station as KFUO-850, coming closer by the mile, in Clayton (St. Louis), Missouri. Little KGAB-650 in Cheyenne, Wyoming is weak but still readable, and in the clear. The fades take it totally out, then it re-emerges for several minutes at a time. The Glen Beck program is on. It started after the news at 1400L CDT. 54 miles to the river. And one hour. I've got to do something.
I pull off the exit at Warrenton, Missouri, thinking I will attach a four foot length of wire to the truck antenna and let it trail in the wind while I drive. I've used this technique before to gain some signal strength and pull in distant DX. I attach the wire and continue on down I-70 towards St. Louis. Signals are marginally better, but the 770 KHz splatter is killing KKZN-760, and KOA-850 has finally disappeared under St. Louis's KFUO-850. Wyoming's KGAB-650 hangs in there, barely.
Traffic builds as I approach the river. The only station left is KGAB-650. It is right at the noise level. At exactly 1505L I cross the Mississippi. Just over the bridge I faintly hear Glen Beck say a few words just above the noise level - what, I don't know - but I can recognize his voice. Then - gone. KGAB fades below the noise for good.
I am in Illinois. To the left of me I pass two AM radio stations. One has an array of four towers and the other six. The receiver desenses so badly that it overloads. I press on wondering what will happen next.
Pocahontas, Illinois. It is 1545L time. Hurriedly, I pull off the exit and into the motel parking lot where I will stay for the night. After registering, I check the truck radio again. Surprisingly, 760 KHz is clear of splatter - but nothing but noise is heard - and no KKZN. 850 KHz is occupied by St. Louis's overwhelmingly strong KFUO. Weak but steady, 650 KHz plays the country music of Nashville's WSM. KGAB-650 is gone, forever.
Quickly I grab the Tecsun PL-600 out of the truck and tune to 760 KHz. I put the headphones on. Something is there just at the noise level, but what?
In a greater hurry, I dig for the 24-inch passive loop I constructed this winter. The PL-600 is still two feet from it when the signal on 760 KHz comes right up out of the noise, nearly arm chair level in the headphones. It is Progressive Talk Radio, KKZN-760, Denver, Colorado! Unbelievable! A new personal daytime mediumwave DX record of 827 miles! Imagine hearing the front range of the Rocky Mountains - some 36 miles east of the Mississippi River in Illinois - IN THE DAYTIME!
ACTUAL COMPUTED GREAT CIRCLE DISTANCES
KKZN-760 (50KW) Denver, Colorado to Pocahontas, Illinois: 827 miles
KGAB-650 (8.5KW) Cheyenne, Wyoming to I-270 & Mississippi River: 791 miles
Who knows how far into Illinois I could have heard KKZN-760? With the interference from KCCV-760 gone, its signal was still respectable off the 24-inch loop at the town of Pocahontas, some 36 road miles east of the Mississippi River. My guess is another 50-100 miles, closing in on 1000 mile daytime DX!
What makes the difference in long distance daytime DX? Clear co-channels and clear adjacent channels are very important. Flat, unobstructed terrain I'm sure is important too. Ground conductivity is very important. Ground conductivity from Denver to central Missouri ranges from 15-30 millimhos per meter. From central Missouri eastward to the Mississippi River it drops to 8, then rises back to 15 east of the Mississippi River. Did partial fog along the distance also make a difference? Possibly, but I will never know for sure what effect it had.
It is remarkable what a 24-inch tunable, passive loop will do for a signal seemingly buried in the noise at 827 miles distant. I was astounded.
THE PLAYERS: WESTERN END
KHOW-630, Denver, CO 5KW News-talk
KKZN-760, Thornton, CO (Denver) 50KW Progressive talk
KOA-850, Denver, CO 50KW News-talk
KGAB-650 Cheyenne, WY 8.5KW News-talk
THE PLAYERS: EASTERN END
KJSL-630 St. Louis, MO 5KW Religious
KCCV-760 Overland Park, KS 6KW Religious
WEW-770 St. Louis, MO Variety/ethnic music
KFUO-850, Clayton, MO (St. Louis) 5KW Religious