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1st adjacent AMs with significant daytime overlap of their 2.5 mV/m contours

In looking for some information, I found a concise list of 50 kW daytime power AM facilities. It's from several years ago, but it is still useful. I like it better than the ones that just list the 50 kW fulltime facilities, since even a 50/5 DA-N, DA-1, or DA-2 facility may have a maximum IDF that exceeds a 50 kW nondirectional IDF. I know that people here were talking about a 5 kW night, highly directional station from California that was heard regularly in Hawaii. Can't remember which station that was.

http://www.airlinepilotcentral.com/files/am radio station guide.pdf
 
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@Piano88:

I'm culturally remiss here, never having been farther west (or north) than Duluth. So all I know are east coast stations.

So as far as ratings go, one might have to go back to the early 60's to find any GYer with #1 numbers in a respectable market -- if ever.

My favorite station WNOR reportedly got their format clock punctually cleaned by the bigger-signalled WGH. But with luminaries such as Jerry Blavat, I'd think that Philly's WHAT 1340 might have concerned some competing folks back then.

In the late 60's - early 70's, WGBB 1240 on Long Island would show very well, as far as Nassau-Suffolk stations were concerned. WGBB was Chicken Rock in the day, and more top 40 at night. This fellow named The Vieser really sounded great 7-mid. But the NYC stations such as WABC and WRFM dominated the Nassau-Suffolk book. WGBB used to compare ratings -- Long Island stations only -- with WGLI 1290. Despite being maybe 20 miles from each other, there was no signal overlap. Yet, WGBB and WGLI were the top 40 'rivals' in the book. (I did news at WGBB for awhile, and the two stations used to prank each other with phone calls .... fun times).

*Maybe * a WNHC 1340 New Haven would disturb competitors, especially at night, 7-mid. But staid, MoR WELI 960 would consider them a moth flying around the tower lights for the majority of the survey.

Our nearby Scranton/Wilkes-Barre market had three GY's. Still does. But even at the pinnacle of WBAX 1240's Top 40 legendry, they (and every other station) got swamped in the ratings by WARM The Mighty 590.

That would be neat, Piano88, if someone could archaeloge a GY station that was undeniably #1 12-plus.
 
Another problem coming up with an example may relate to 5000 watt Class IIIs having MOR/AC/Full Service formats, and having higher ratings than the Top 40 that was relegated to a 1000 watt daytime, 250 watt nighttime Class IV, which also had fewer advertisers because they didn't like Rock and Roll. Only in the really large markets would you have a 50000 watt Top 40 station, and then only because there were several 50000 watt stations. In the 1970s, you saw the better facilities start to go Top 40, but then quickly switch to AC because the kids were starting to listen to AOR on FM. There were some strange dynamics going on there with the formats back then, and probably today.
 
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At least judging from the Radio Locator maps, the 1st adjacent situation with which I am familiar regionally, 1230 WYTS in Columbus and 1240 WHIZ in Zanesville, actually does not involve any 2.5 mV/m overlap ... at least not today. But a few years back, when WYTS ran IBOC, you could be within 10 miles of Zanesville and hear the IBOC hash under WHIZ.
I don't remember at exactly what point WHIZ's signal was strong enough to completely overtake the hash, but I do remember it being not too far west of the city limits.
I also don't remember exactly when WYTS dropped IBOC. No idea if WHIZ complained, but I wouldn't blame them if they did.
For reference's sake, the two towers are approximately 55 miles apart. Both signals are 1,000 watts (daytime; at night, WHIZ drops to 960 watts). When I lived almost exactly halfway between the two in Thornville, Ohio (albeit a bit closer to WHIZ), WYTS was always stronger, I figured because of better ground conductivity between us and Columbus.
 
cyberdad said:
(BTW: All joking aside, I'm a big fan of the services provided by radio-locator. We all know they're not perfect, but given the scope of what their mission is, I think they do a very creditable job.)
Click to expand...

I suspect they do as good as job as they do because their original algorithm for plotting service contours was written by MIT students, back when it started.
 
I was considering a few current (and former) overlap situations here in southern California, and I think we have a few that could contend in the category of greatest overlap.

1030 XESDD vs 1040 KURS -- These 2 stations are 32.4 miles apart. KURS runs 360 watts and XESDD runs 5 kW, both non-directional. I think at least the stations' 5 mV/m contours overlap, possibly even as high as 8 mV/m or so, according to my preliminary calculations. (I think the overlap falls a little short of 10 mV/m, though.)

1390 XEKT vs KLTX -- These are almost 128 miles apart, with some saltwater path. Both stations run 5 kW, with KLTX being directional. I suspect at least their 1 mV/m contours overlap, possibly as high as 1.5 or 2 mV/m.


Also there's a few from the past that I think had a significantly higher overlap, although these were temporary. Any of you remember the brief time several years ago where we had some Mexican AM stations on frequencies that significantly interfered with some other stations, for a little while? (The stations are currently 620 XESS - which may have a little overlap with KTAR, but not likely more than 0.3 or 0.5 mV/m, 1030 XESDD and 1700 XEPE.)

Anyway, before XESDD was on 1030, I think it was on 920, and had a pretty potent signal in El Cajon. I don't have any data, but based on my recollection and doing some guesswork, I'd guess that 920 overlapped with 910 KECR to the tune of like 15-25 mV/m or so.

Also XEPE was briefly on 550, then on 560, under, I think, the XEKTT calls. When they were on 560, I suspect they had something like a 2 mV/m or more, possibly as high as 5 mV/m overlap with KBLU. While on 550, they were quite short-spaced with 540 XESURF (it may have been known as XETIN or any other number of calls at the time like XEBACH, XEJAZZ, etc), and I think could have easily had a 50 mV/m overlap, possibly even 100 mV/m!


Maybe someone who knows more about the technical data of the stations I mentioned could advise as to what the actual figures would be?


Oh, and ...

Beat that. :)
 
Cudgeled memory here recalls the time when WGHT 1500 Pompton Lakes NJ and the now-dark WRAN 1510 Dover NJ were on the air.

The always-entertaining How Far Is It page lists the two cities as being 16 miles apart, as the cow flies.

Here's WGHT.
http://www.radio-locator.com/cgi-bin/pat?call=WGHT&service=AM&status=L&hours=D

Dover is that little beige area dissected by the blue contour southeast of the Hopatcong circle.

I don't have the WRAN daytime map available. For what it's worth, I do know that their nighttime pattern was a long, skinny bowtie thing that was aimed sort of 11:30 - 5:00.
And that WKBW used to give the station fits at night.
In Dover.
 
joebtsflk1 said:
Went snooping for some class Bs w/1st adjacent 2.5 mV/m overlap, and I'll nominate 600 WSOM Salem OH http://radio-locator.com/cgi-bin/pat?call=WSOM&service=AM&status=L&hours=D and 610 WTVN Columbus http://radio-locator.com/cgi-bin/pat?call=WTVN&service=AM&status=L&hours=D
The 2.5 mV/m daytime contours appear to touch. I'm thinking it wasn't just Class Cs/IV's that got interference waivers, but in the case of the class Bs, how?
Click to expand...

Given the ground conductivity in the part of Ohio where WSOM and WTVN overlap, I tend to doubt WSOM gives WTVN too many problems. Judging from the map, that area is at least 70 miles out of Columbus, somewhere outside Coshocton. I don't remember noticing any really bothersome interference on WTVN on my few trips to that part of Ohio, but it is possible.
 
The How Far Is It page says that Sunbury PA and Philadelphia are 105 miles apart.

1070 WKOK is 10,000 watts omni during the day.
http://www.radio-locator.com/cgi-bin/pat?call=WKOK&service=AM&status=L&hours=D

1060 KYW is the louder of the two here in most of Schuylkill County's population belt. There is no overlap or splash.
http://www.radio-locator.com/cgi-bin/pat?call=KYW&service=AM&status=L&hours=U


I realize that 105 miles is a bit outside the range of the topic, but check out WKOK's directional night pattern:
http://www.radio-locator.com/cgi-bin/pat?call=WKOK&service=AM&status=L&hours=N
Right AT Philadelphia. Weird.

Again, there is no overlap at night here, either. I can't remember hearing WKOK at night.

(For reference: WKOK originally signed on to 1240. 1070 was, of course, vacant. I forget the year -- the decade, even -- when they moved to 1070. Engineers here will be able to explain how they got that nighttime permission to throw something like the equivelant of 5000-or so watts right at established KYW. That's a lot of wattage involved vis-a-vis the two stations)
 
First adjacent didn't used to be a nighttime skywave restriction. It was assumed that if the 0.5 mV/m groundwave signals did not overlap, then there was not a problem. Presently, there is a restriction, but it is not as severe as you might think. Have to look it up. Think it protects the 0.1 mV/m groundwave of the Class A station like KYW.
 
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David, would you have some idea of what the specs / overlap are, or were, for the following Mexican border stations?
1030 XESDD vs 1040 KURS
920 (Tijuana) vs 910 KECR, several years ago
550 (Tijuana) vs 540 (now XESURF), several years ago
560 (Tijuana) vs 560 KBLU
620 XESS vs 620 KTAR
1390 XEKT vs 1390 KLTX

Also what, if you could refresh my lacking memory, was the frequency/site move sequence for the south-of-border stations that are now 620 XESS, 1030 XESDD, 1390 XEKT and 1700 XEPE? I think 1030 was on 920, 1390 was on 1380, and 1700 was on 1600 then 550 then 560, but I'm not sure, and idk about 620's origins.
 
KYW was Class I-B. It is directional with a two tower array which has a sort of Figure 8 pattern with a shallow null to the SW and deeper nulls to the NE toward WEPN. It is maximum to the SE and NW.

KGO (was I-B) is directional with three towers.

KOA is Class A nondirectional, but has an efficiency restriction to the minimum for Class A.

WRVA (was I-B) has a two tower pattern with maximum directions to the SE and NW.

WBZ and WWL (were I-A) are directional with two towers, and direct their signals inland. WTAM (I-A) moved for a while and was directional with a drop line from a guy wire for the second radiator. It also went inland. It is back to nondirectional.

WLW (I-A) was directional for a time when it was 500 kW, to protect CFRB Toronto, which was on 690 at the time. It was a very simple design like David has described, like a parasitic second radiator or just using the transmission line for phasing.

Most of the duplicate former I-Bs on the same frequency (mostly >= 1000 kHz) use directional antennas with three tower in line cardioid patterns to protect each other at night.

CBM 940 Montreal moved slightly, and to protect existing US and Mexican stations and to concentrate the signal in Canada, went very slightly directional. They have moved again and are nondirectional under private ownership.

Unlike FM directional antennas, AM directionals concentrate their signals with IDFs that exceed the nondirectional IDF for their power level if they are operating properly without excessive system losses. FM DA ERPs in the US only represent the maximum direction or directions.
 
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Schroedingers Cat says >>>CBM 940 Montreal moved slightly, and to protect existing US and Mexican stations and to concentrate the signal in Canada, went very slightly directional. They have moved again and are non-directional under private ownership.<<<

I believe that 940 CBM/CINW Montreal was slightly nulled away from Mexico City to protect 940 XEQ. Both were originally Class I-B stations. XEQ operates non-directional. I'm not sure that the original NARBA rules would permit two non-directional 50kw stations to operate as close as Montreal and Mexico City. I believe there are/were only two channels with two non-directional 50kw stations: 540 and 1070. CBK Regina, Class I-A, was originally the only 50kw non-directional station on 540. But because Mexico protested that it didn't get enough clear channel stations, XEWA San Luis Potosi was allowed to operate on the same frequency, also as a Class I-A. And 1070 CBA Moncton and KNX Los Angeles were deemed so far apart that both operated 50kw non-directional, but both were considered Class I-B, even with their non-directional signals. (Today CBA has moved to FM and most people think XEWA has reduced its power and may also be headed for FM. And when 940 in Montreal goes back on the air, it may not be at 50,000 watts.)

If 940 was a third exception to the one-50kw-non-directional-per-channel rule, I'm not sure what the reasoning would be. Montreal got 690 as a Class I-A, the only non-directional station on that frequency. And it got 940 as a Class I-B, having to co-exist with XEQ.

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Getting back to the question of any Grave Yard AM leading its market, for a while 1240 WMMB Melbourne FL was #1 with an Adult Standards format, perhaps a Music of Your Life affiliate. This was back in the 90s. That's the only one I know of.

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For adjacent channel AM stations, how about 580 WTAG Worcester and 590 WEZE Boston? Both are 5000 watts day and night. Two low-on-the-dial 5000 watt stations only 42 miles from each other. I assume both have directional signals pointed away from each other. Up the dial at 830, WCRN identifies itself as "WCRN Worcester-Boston." So for WCRN, it uses Boston as its unofficial second city of license while its main competitor, WTAG, cannot be heard anywhere near Boston.
 
What might have happened is that CBM began diplexing with CBF, and because the tower was so efficient at 940, they had to go directional. They probably couldn't increase toward Mexico City or stations like KIOA. In any event, the second radiator of whatever description had a field ratio of 0.12 compared to the main tower's 1.0 field ratio, the lowest field ratio in the whole Region II Database for any two tower DA. That would mean that if there was 50000 watts radiating from the main tower, there was only 720 watts radiating from the second radiator. When I called the CBC in Montreal, they didn't even realize that CBM was directional until they got out their engineering reference material. Maybe that was a drop line from a guy wire also. Many FM DAs just use tower mounting with standard nondirectional bays to be directional, so that may not be immediately apparent when looking at the antenna either.
 
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Now that I think about it, I had an email exchange several years ago about first adjacent skywave interference to Class As with Dave Doherty, and we came to the conclusion that the 0.5 mv/m groundwave of the Class A was protected from the 0.25 mv/m 10% skywave of the first adjacent interfering signal. Otherwise, there couldn't be any adjacent situations like WFAN/WSCR, WABC/WJR, WABC/WBBM, WCBS/WLS, etc. except grandfathered ones.
 
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