Information please; history of AM Daytimers

[Schroedingers Cat]

A couple of the posters here were having that very conversation by email about CKLW changing it's day pattern. Anyone know why they changed? WSGW on 790? The old pattern is on a QSL card signed by Ed Buterbaugh and can be found by clicking through on Wikipedia. The new pattern (easily seen on radio locator ) seems to pull in more to the west and northwest. Anyone have access to really old databases? I think they used the same five towers, but different phases or and or field ratios. The basic pattern shape was similar.

 

[gr8oldies]

I once had the old CKLW pattern map, and at least coming into Ohio it doesn't look different. CKLW's night pattern was changed to pull the signal in from the U.S. and feed most of it east into Canada during the 90s

 

[Schroedingers Cat]

I have been downloading the FCC Region 2 Database since about 1996, and there are only two patterns in that database. Many Canadian stations have multiple records, some from way back, some never built, some records for stations that don't exist but were put in as allotments.

From my memory, the CKLW day pattern is not as good to the northwest as it used to be. The night pattern always had to protect Mexico, hence the change which eliminates the huge lobe to the SW in the day pattern. There could have been some minor changes in the patterns.

WSGW 790 went to 5000 watts day circa 1960, but I don't know if that had anything to do with the CKLW change.

 

[Schroedingers Cat]

CKLW QSL With Coverage Map:

http://en.wikipedia.org/wiki/File:CKLWCoverage1.jpg

CKLW Radio Locator Coverage Map:

http://www.radio-locator.com/cgi-bin/pat?call=CKLW&service=AM&status=F&hours=D

 

[Greg Strickland]

There are different things here in this discussion, audio quality, channel interference and the lower frequency advantage. They add up to an impression given by the station.

 

[rfry]

... From my memory, the CKLW day pattern is not as good to the northwest as it used to be. ....

The daytime coverage shown on that Radiolocator link for the "blue" (0.15 mV/m) contour of CKLW is roughly the same as identified to be the 0.5 mV/m contour on CKLW's 1976 QSL card.

The link next below shows the parameters for CKLW's daytime pattern. Their 1 km IDF toward the NW is less than 1000 mV/m, compared to their daytime RMS of 1888 mV/m @ 1 km.

http://i62.photobucket.com/albums/h85/rfry-100/CKLW_Day_Pattern.gif

OTOH, WJR's 1 km IDF and RMS is 2845 mV/m, from a site about 17 km NW of CKLW.

The Radiolocator pattern for WJR linked below shows their 0.5 mV/m contour near Grand Rapids (in magenta) at only a short distance more than shown for CKLW's 0.5 mV/m contour on their QSL card. But that close an agreement would be unlikely, due to the difference in ERPs from the two stations toward that sector, and because the path from WJR is about 17 km shorter.

http://www.radio-locator.com/cgi-bin/pat?call=WJR&service=AM&status=L&hours=U

So maybe CKLW's QSL card shows their 0.15 mV/m contour, rather than their 0.5 mV/m contour.

And if that is true, then it is interesting to observe that even with CKLW's daytime 1 km IDF of 3400 mV/m toward Indianapolis, WJR's 0.15 mV/m contour extends a bit further there than does CKLW's.

RF

 

[gr8oldies]

I don't remember when we lost The Big 8 on the way to our vacation 50 mi. north of Grand Rapids but it was almost inaudible there. At night CKLW blasted in there (opposite of home)

 

[Schroedingers Cat]

Near Big Rapids, MI, the NEXT STRONGEST SIGNAL was WMAQ 670 Chicago until new stations and new facilities such as WTCM 580 came on. If you go to Doug Vernier's AM signals by Zip Code program, it predicts that others would be stronger than WMAQ/WSCR but they aresn't. Of course, WTMJ 620 is also now in the milieu, but then it was always there, just weaker. If you had an outside antenna, loop, and or preamp, you could get a whole bunch of stations there in the daytime.

 

[Schroedingers Cat]

Let me clarify that local WBRN had the strongest AM signal. Sorry for the confusion. It was close enough to the lake that the IL and WI stations were often stronger than the East Michigan signals.

 

[gr8oldies]

Top 40 in that vacationland was WOKY (a little noisy) and WGRD (1410) in Grand Rapids.

 

[rfry]

The Radiolocator pattern for WJR linked below shows their 0.5 mV/m contour near Grand Rapids (in magenta) at only a short distance more than shown for CKLW's 0.5 mV/m contour on their QSL card. But that close an agreement would be unlikely, due to the difference in ERPs from the two stations toward that sector, and because the path from WJR is about 17 km shorter.

(Later) The FCC MW propagation curves when used for WJR show a distance of about 162 miles to their 0.5 mV/m daytime contour for 8 mS/m conductivity. According to the M3 chart, that is the conductivity along the path from their tx site along a radial through Grand Rapids.

This FCC value of 162 miles agrees well with the Radiolocator plot for WJR's 0.5 mV/m contour on that radial.

 

[Schroedingers Cat]

In central Michigan, many recent applications online show much less than 8 mmhos/m.

With the outside vertical (actually 20 feet of twinlead twisted together from an outside TV antenna) and a preamp, you could also get WIND, WLS, WCFL and many others quite well.

 

[rfry]

In central Michigan, many recent applications online show much less than 8 mmhos/m.

Just to note that, whatever the real earth conductivity, the propagation paths from WJR and CKLW through Grand Rapids are nearly aligned in azimuth.

So regardless, CKLW could not ~match WJR's daytime field in/near Grand Rapids as shown on the CKLW QSL card, given CKLW's significantly reduced ERP and longer path on that radial when compared to WJR.

 

[Schroedingers Cat]

If these were real measurements of CKLW, I suspect that there might have been some daytime skywave involved. I can't see it either, given that CKLW's major lobes are the only places where the inverse field exceeds WJR's.

 

[gr8oldies]

Sometimes you have to take maps made to promote sales with a grain of salt though CKlW's map was pretty dead on for Ohio. WJR was the weaker of the 2 at my Ohio location but they were even in Lima

 

[rfry]

Sometimes you have to take maps made to promote sales with a grain of salt...

Agreed.

... though CKLW's map was pretty dead on for Ohio. WJR was the weaker of the 2 at my Ohio location but they were even in Lima

Lima is located at roughly the same distance, and along roughly the same radial to/from both WJR and CKLW. The location of Lima is rather well up on CKLW's major daytime lobe toward the SW, so for that ~107 mile distance and regardless of the real ground conductivity, CKLW could reasonably have somewhat greater daytime field intensity there than WJR.

Below are the groundwave values for both facilities in/near Lima, based on the FCC M3 map.

Daytime

CKLW 1.99 mV/m
WJR 1.44 mV/m

Nighttime

WJR 1.44 mV/m
CKLW 0.35 mV/m

RF

(edit) added the distance