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Early Development Of AM BC DAs

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CK-722
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Early Development Of AM BC DAs

Post by CK-722 » Sat Oct 24, 2020 11:25 pm

39 DAs were operating before the start of World War II. In Michigan, there were 3 to 5 operating, WWJ, WXYZ, WFDF, and possibly WKZO and WOOD, by circa 1942.

https://www.radioworld.com/columns-and- ... st-antenna

It appears that the WWJ DA nulls toward WPEN and KPRC from 8 Mile Rd. were such a problem after 1941, that after being allowed 5 kW nondirectional at Night on special authorization between 1935 and 1941, renewed monthly, the signal was weak enough to the South with the new DA that they applied to move to River Rouge, near Coolidge Hwy. and Goodell St. in 1946. From the standpoint of a Night site, it would have been good at the time. I don't know when the FCC started allowing two site operations, but the 8 Mile Day site with 5 kW nondirectional and a 186 degree tower was unbeatable by 1950, when population began migrating toward further out areas of Oakland and Macomb Counties. From River Rouge, the nulls toward WPEN and KPRC at Night wouldn't have mattered nearly as much. And the population in Oakland and Macomb Counties was quite close in until then.

WWJ FCC History Card-Takes A Long Time To Load- ~100 years of History

http://licensing.fcc.gov/cgi-bin/prod/c ... r_id=68876

WFDF was the first station in Michigan to use a DA during the Daytime.

WKZO was always a thorn in the side of WOW 590 Omaha, from it's beginnings as a Daytime only station, to being 250 watts nondirectional Night, to being required to be 1000 watts Night experimentally directional, to being authorized to use 5000 watts directionally at Night, but required to be directional until 10 AM during Omaha morning drive and critical hours. This inadvertently also allowed WKZO to double its signal strength in Grand Rapids during West Michigan morning drive hours.


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CK-722
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Re: Early Development Of AM BC DAs

Post by CK-722 » Sun Oct 25, 2020 2:00 pm

The extended Daytime use of the DA after WKZO went to 5 kW Night, from 6 PM to 10 AM, went on until 1968, after reviewing the History Card again. This was due to WOW insisting that it needed protection of it's secondary service area during critical hours year around. This did allow them to have a much stronger signal in Grand Rapids during CH and morning drive. The nulls around Kalamazoo weren't as problematic then, as they fell over very thinly populated areas.

This map would seem to indicate that WOW would have rather extreme fading problems.

https://www.fccdata.org/?lang=en&facid=50313


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Rich F.
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Re: Early Development Of AM BC DAs

Post by Rich F. » Mon Oct 26, 2020 5:06 am

CK-722 wrote:
Sun Oct 25, 2020 2:00 pm
... This map would seem to indicate that WOW would have rather extreme fading problems. https://www.fccdata.org/?lang=en&facid=50313
So it does (i.e., where their 0.5 mV/m nighttime skywave interferes with their own 2 mV/m day&night ground wave).

WKZO running 5 kW directional until 10 pm contributed to that "trashing" to some extent, no doubt.



CK-722
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Re: Early Development Of AM BC DAs

Post by CK-722 » Mon Oct 26, 2020 7:46 am

WOW being 5 kW nondirectional at all hours, serving the M-3 estimated excellent conductivity regions, and large rural areas surrounding Omaha, made it considered to be a Quasi Clear Channel. WKZO's pattern had/has to address clipping of the vast NIF contour area, not just the WOW site. It looks like it took two closely spaced azimuth nulls to accomplish this.

WKZO ran DA from 6 PM until 10 AM the next morning until circa 1968 to protect WOW during drive time and critical hours. That would be from 5 PM to 9 AM in Omaha.

https://transition.fcc.gov/Bureaus/MB/D ... -96583.pdf

Image


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k8jd
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Re: Early Development Of AM BC DAs

Post by k8jd » Mon Oct 26, 2020 10:43 pm

I was born at the end of WW2 but remember seeing that two tower array on 8 mile rd whenever we went to Northland , the brand new shopping center !!
Also recall seeing the two towers down off joy road before WXYZ moved to Southfield.
AND recall when WJBK had TWELVE towers , raally big array down in Lincoln Park.



CK-722
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Re: Early Development Of AM BC DAs

Post by CK-722 » Mon Oct 26, 2020 11:20 pm

WXYZ 1270 moved to 10 Mile Rd. in 1959 as I recall reading in the History Card. I think they wanted to consolidate all operations for WXYZ, WXYZ-FM, and WXYZ-TV at Broadcast House. It also let WXYZ have a good signal in the growing areas of the Metropolitan Area.


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Same (x, y, z), different (t)

Your bullet missed my trial balloon.

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k8jd
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Location: Commerce, MI

Re: Early Development Of AM BC DAs

Post by k8jd » Tue Oct 27, 2020 4:13 pm

I worked at Broadcast house for a few years . Between my RCA mobile and Motorola jobs.
I was on the AM/FM side of the building :D
The two tower AM site was about 1/4 mile south of the main compound.



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