Critical Hours on 1510 AM

Here in Nashville, this frequency is home to 50K WLAC - which by virtue of high dial position and poor ground conductivity does not have an especially great signal, even here in close-in west Nashville. During critical hours, I'm getting a strong signal (on a clock radio no less) fading in/out under WLAC but I've been unable to ID it conclusively. It's occasionally nearly swamps WLAC. Format sounds like talk, quite possibly sports.

My guess (and it's only a guess) is that this is KCTE in Independence MO which runs 10K daytime only with no change for critical hours. As a daytime only I assume it would light up at 6am, it's in the same time zone, and it's west of here so it might benefit from more lingering skywave propogation.

Am I thinking correctly about how critical hours DX works in terms of the direction from which we'd get our best signal?

Looking at the FCC's database and the formats for all the stations I'd consider, it sounds like you're right. WLAC must be having some real troubles if they can't fill in the null that KCTE has to leave for them in that direction.

I wouldn't quite classify 1510kHz as "almost shortwave." Not sure where you got that quote from, but it wasn't me. And as for poor ground conductivity and enhanced propagation conditions, if he's living IN Nashville, where a 50,000-watt WLAC should be covering the whole of the city/county with no conductivity or propagation issues, that null would seem to be having some problems. It should be covering the city proper. Even with the nighttime pattern they use, they're putting out enough juice that conductivity and propagation shouldn't be a problem that close to the transmitter.

JoshTheRadioDude said:

I wouldn't quite classify 1510kHz as "almost shortwave." Not sure where you got that quote from, but it wasn't me. And as for poor ground conductivity and enhanced propagation conditions, if he's living IN Nashville, where a 50,000-watt WLAC should be covering the whole of the city/county with no conductivity or propagation issues, that null would seem to be having some problems. It should be covering the city proper. Even with the nighttime pattern they use, they're putting out enough juice that conductivity and propagation shouldn't be a problem that close to the transmitter.

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The Radio-locator map seems to imply that the southwest and southeast corners of Nashville get a little less than 2.5 mV/m during the day! WLAC probably covered all of Nashville with 5 mV/m in the past, before Nashville grew.

I was in Nashville for the 1993 WTFDA convention, and I noticed that all the AMs had lousy coverage (even WSM, though it covered Nashville itself, seemed to fall short of what one would expect from even a Class B FM during the day). (Yes, I know, no Class B in Nashville, but that's for comparison).

Further looking at Radio-locator, I note that KCTE's nulls are not that deep, so it could cause issues before the sun sets over KC (I wonder if the pattern got licensed before 1959, when the concept of "critical hours" was introduced?)

I also agree with DavidEduardo's use of "almost shortwave", especially as he put it in quotation marks, as the term is subjective in nature. As you go higher in frequency in the MF spectrum, propagation by "true groundwave" becomes less effective (especially where soil conductivity is low) and skywave propagation becomes more efficient. There is no sudden change - no significant difference in propagation at 2995 kHz (MF) and 3005 kHz (HF, also called shortwave). For that matter, one could say the 75m/80m amateur band is "almost the AM band" - lousy for distance during the day, good at night, and - to this day - AM phone is still in use!

bgfred said:

Here in Nashville, this frequency is home to 50K WLAC - which by virtue of high dial position and poor ground conductivity does not have an especially great signal, even here in close-in west Nashville. During critical hours, I'm getting a strong signal (on a clock radio no less) fading in/out under WLAC but I've been unable to ID it conclusively. It's occasionally nearly swamps WLAC. Format sounds like talk, quite possibly sports.

My guess (and it's only a guess) is that this is KCTE in Independence MO which runs 10K daytime only with no change for critical hours. As a daytime only I assume it would light up at 6am, it's in the same time zone, and it's west of here so it might benefit from more lingering skywave propogation.

Am I thinking correctly about how critical hours DX works in terms of the direction from which we'd get our best signal?

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First of all, see you've only posted 11 times, so I assume you're fairly new around here. If that's the case, welcome aboard! And don't be shy about contributing!

I have to say, what you described in your post doesn't surprise me. And you're correct in how critical hours DX works as relates to WLAC. David gave you a pretty good thumbnail explanation of the physics involved, and 1L6E6VHF expanded on it. We can debate on whether or not 1510 is "almost shortwave." Personally, IMHO, that's not a bad way to look at it. Subjective, of course. The fact is the high end of the AM broadcast band has better skywave propagation than the lower end. It normally starts sooner during the afternoon and ends later in the morning. In fact, during winter when days are shortest, it's not very unusual for skywave conditions present all day long...especially on the upper end of the band.

As posted earlier, I spent a night in Clarksville, TN, earlier this month. As you probably already know, and as I discovered, WLAC's signal is lousy out there at night with their null to the northwest. And it's no great shakes non-directional in the daytime, either....despite Clarksville being only about 40 miles from a 50kw stick. So indeed, the poor ground conductivity combined with a channel that works well for skywave is the perfect setup for WLAC to get trashed by whatever atmospheric conditions bring in.

Finally, I wouldn't be surprised if KCTE might be "a little less than diligent" about maintaining their pattern. If that's true, that certainly wouldn't help matters for WLAC.

bgfred said:

Here in Nashville, this frequency is home to 50K WLAC - which by virtue of high dial position and poor ground conductivity does not have an especially great signal, even here in close-in west Nashville. During critical hours, I'm getting a strong signal (on a clock radio no less) fading in/out under WLAC but I've been unable to ID it conclusively. It's occasionally nearly swamps WLAC. Format sounds like talk, quite possibly sports.

My guess (and it's only a guess) is that this is KCTE in Independence MO which runs 10K daytime only with no change for critical hours. As a daytime only I assume it would light up at 6am, it's in the same time zone, and it's west of here so it might benefit from more lingering skywave propogation.

Am I thinking correctly about how critical hours DX works in terms of the direction from which we'd get our best signal?

Click to expand...

First of all, see you've only posted 11 times, so I assume you're fairly new around here. If that's the case, welcome aboard! And don't be shy about contributing.

I have to say, what you described in your post doesn't surprise me. And you're correct in how critical hours DX works as relates to WLAC. You're near the eastern limit of the Central time zone, while Kansas City is quite a distance to the west of you. Sunrise and sunset are later there. David gave you a pretty good thumbnail explanation of the physics involved, and 1L6E6VHF expanded on it. We can debate on whether or not 1510 is "almost shortwave." Personally, I don't think that's a bad way to look at it...subjectively. The fact is the high end of the AM broadcast band has better skywave propagation than the lower end. It normally starts sooner during the afternoon and ends later in the morning. In fact, during winter when days are shortest, it's not very unusual for skywave conditions present all day long...especially on the upper end of the band.

As posted earlier, I spent a night in Clarksville, TN, earlier this month. As you probably already know, and as I discovered, WLAC's signal is lousy out there at night with their null to the northwest. And it's no great shakes non-directional in the daytime, either....despite Clarksville being only about 40 miles from a 50kw stick. So indeed, the poor ground conductivity combined with a channel that works well for skywave is the perfect setup for WLAC to get completely trashed by whatever atmospheric conditions bring in.

Finally, I wouldn't be surprised if KCTE might be "a little less than diligent" about maintaining their pattern. If that's true, that certainly wouldn't help matters for WLAC.

bgfred said:

Here in Nashville, this frequency is home to 50K WLAC - which by virtue of high dial position and poor ground conductivity does not have an especially great signal, even here in close-in west Nashville. During critical hours, I'm getting a strong signal (on a clock radio no less) fading in/out under WLAC but I've been unable to ID it conclusively. It's occasionally nearly swamps WLAC. Format sounds like talk, quite possibly sports.

My guess (and it's only a guess) is that this is KCTE in Independence MO which runs 10K daytime only with no change for critical hours. As a daytime only I assume it would light up at 6am, it's in the same time zone, and it's west of here so it might benefit from more lingering skywave propogation.

Am I thinking correctly about how critical hours DX works in terms of the direction from which we'd get our best signal?

Click to expand...

1510 out of Nederland, TX (KBED) is a daytime only simulcast of CBS Radio Sports 1450......5KW two tower N/S which would put the signal..

WLAC may not cover Nashville entirely, but it sure pays us a nightly visit down here in SE Texas. WLAC is very comparable to the signal I pick up from our 50kW neighbor to the east, WWL.

KBED, over in CW's neck of the woods, likely can hear WLAC in their monitors after shutting down. As good as the signal comes into Houston, I'd figure Beaumont likely gets it even stronger and more reliably than we do.

Here in northeast PA, I've heard the station out of Boston -- the former WMEX -- doing sports. Might they be them or that be them?

Also have heard WLAC in these parts nighttimes, even via a casual tune-in. WLAC has a pretty good night signal. They were the dominant 1510 on the Gulf Coast of Florida and even inland (Lady Lake) the past few times I've been that way

purpledevil said:

WLAC may not cover Nashville entirely, but it sure pays us a nightly visit down here in SE Texas. WLAC is very comparable to the signal I pick up from our 50kW neighbor to the east, WWL.

KBED, over in CW's neck of the woods, likely can hear WLAC in their monitors after shutting down. As good as the signal comes into Houston, I'd figure Beaumont likely gets it even stronger and more reliably than we do.

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Back in the top40 70s, WLAC was a button on my AM radios...(after KCAW...yes Country And Western would sign off)....KCAW's owner was Jimmie Joynt...who sold the AM and FM (93.3) w/then callsign KYKR and moved to Dallas to start Superior Broadcast Systems...Cumulus owns the AM, 93.3 was sold to Tichner/Univision and KYKR calls were moved to 95.1 after the previous owner drove B95 into the ground..

Thanks for the replies/discussion! I have not heard this for the last week or two... so still can't ID.