USA AM radio "clear channels"

Hang out, relax, chill, and chat about off topic stuff.

Moderator: dbbubba

USA AM radio "clear channels"

Postby brianroth » Tue Sep 07, 2010 6:30 pm

Gentlemen,

I've spun this off here from a thread in my "installations" section regarding RFI, since the topic is more of a "lounge" subject.

I dug out an Olde book from 1984, entitled "North American Radio-TV Station Guide" to simplify my search for real-deal, 50 kW stations that broadcast with an "omni-directional" pattern, both day and night. From that, I could easily cross reference into the Radio-Locator website.

In order of frequency:

640 kHz KFI Los Angeles (although Locator says non-directional, I am puzzled by the info and pattern map)

http://www.radio-locator.com/cgi-bin/pa ... =L&hours=N

650 WSM Nashville

http://www.radio-locator.com/cgi-bin/pa ... =L&hours=U

660 WFAN in NYC (and another odd pattern for an "omni" day/night)

http://www.radio-locator.com/cgi-bin/pa ... =L&hours=U

700 WLW Cincinnati

http://www.radio-locator.com/cgi-bin/pa ... =L&hours=U

720 WGN Chicago

http://www.radio-locator.com/cgi-bin/pa ... =L&hours=U

750 WSB Atlanta

(and I ran out of my "free access for a day" at Radio-Locator!)

now manually looking through the book for "one 50 kW on a channel":

760 WJR Detroit

820 WBAP Ft. Worth, TX

840 WHAS Louisville, KY

870 WWL New Orleans

890 WLS Chicago

1040 WHO Des Moines, IA

1200 WOAI San Antonio

And, that's what I could find, but couldn't verify that the last few stations were indeed 50 kW "omni" day and night via Radio-Locator. Note also that some AM channels are Mexico or Canada "clear channels", and I skipped over them. Also, it is common for some of the USA "clears" to also have some low-powered stations on the same channel, but located across the continent from the main blowtorch. Example is WWLS here in Oklahoma City at 640 kHz, same as KFI Los Angeles. WWLS runs only 1 kW into a four tower array, which is obviously designed to have a DEEP null towards the west <g>.

Best,

Bri
User avatar
brianroth
Producer
 
Posts: 452
Joined: Sat Nov 07, 2009 1:57 am
Location: Oklahoma City OK

Re: USA AM radio "clear channels"

Postby THEMIXFIX » Tue Sep 07, 2010 6:43 pm

Brian:

That's odd. While I admit I don't know squat about radio, I do know that WFAN used to be WNBC 660.

BUT, when I was growing up, the biggest selling point for W A "Beatle" C (WABC-770) was it had 50,000 Watts of Clear Channel Power, which could have just been their advertising hype...

Image
THEMIXFIX
Go-Fer
 

Re: USA AM radio "clear channels"

Postby brianroth » Tue Sep 07, 2010 6:54 pm

Dear Bob,

I omitted "clear channels" with more than a single "blowtorch". 770 had/has WABC in NYC as well as KOB in Albuquerque NM. That is similar to the situation with KRLD in Dallas and WTIC in Hartford CT on 1080, or KOMA/KOKC here in OKC and WKBW in Buffalo, NY on 1520. Those stations ran/run directional antenna arrays at night (but are typically omni days), as do other combos on other "clear" channels.

It was just a NERD exercise on my part to refresh my memory about TRUE clear channels....hehehe.

Best,

Bri
User avatar
brianroth
Producer
 
Posts: 452
Joined: Sat Nov 07, 2009 1:57 am
Location: Oklahoma City OK

Re: USA AM radio "clear channels"

Postby THEMIXFIX » Tue Sep 07, 2010 8:16 pm

Brian:

Like I said, I don't know squat about any radio transmission stuff, so I just brought up my memories of listening to The Beatles under the covers when I was 12 on WA "Beatle" C, with Cousin Brucie. (Who, by the way, I worked with years later, and he was a GREAT guy, as was Murry the "K", and "Wolfman Jack". Image

Don Anus; I have a good story for another time, but his "nickname" pretty much speaks for itself.

Image
THEMIXFIX
Go-Fer
 

Re: USA AM radio "clear channels"

Postby dbbubba » Tue Sep 07, 2010 10:51 pm

It is interesting that you mention the directionality of a station's signal.
The antenna array for KRLD is two towers that are arranged with one slightly North by North East to the other.
If one was your center the other is at about 2 o'clock with noon being due north.

Like this: ANT #2



ANT #1

I wonder how this array radiates?
It can't radiate towards Hartford.
Danny Brown
(I was going call myself Mr. B because I like people to say "MISTER" when they say my name, but then I pitied the fools.)
User avatar
dbbubba
Producer
 
Posts: 773
Joined: Tue Sep 29, 2009 8:44 pm
Location: Rockwall, Texas (Dallas area)

Re: USA AM radio "clear channels"

Postby brianroth » Tue Sep 07, 2010 11:12 pm

Dear Danny,

I'm a bit fuzzy about the specifics behind directional AM antenna arrays, but I do know the transmitter's signal is fed into the towers (yes, the entire metal structure is a radiator) with phase shift circuits in-line. Due to the phase shifts, the positioning and spacing of the towers, and other voodoo <g>, the result is a bending of the radiated pattern.

Some AMs are "omni" and require only a single stick, day or night. Others are non-directional days, and directional at night, like KRLD. In that case, only one stick is powered daytime, and the other stick(s) with their phasors are activated at local sunset.

Yet other AMs are directional day and night, sometimes with different patterns!

I once had a slight grasp of the math behind all this, but since I never worked with an AM station, my basic understanding has long faded away. I guess the Fun of the 1970's did a bit of bulk erasing of my brain cells. <g> But, I'll poke around for a more scientific explanation.

Best,

Bri
User avatar
brianroth
Producer
 
Posts: 452
Joined: Sat Nov 07, 2009 1:57 am
Location: Oklahoma City OK

Re: USA AM radio "clear channels"

Postby brianroth » Tue Sep 07, 2010 11:23 pm

Dear Bob,

I had "radio in my blood" since I was a young child. By high school, I had landed a gig at a small, local FM rock station (KWHP) doing most of their tech work part time at minimum wage ($1.60/hour in the early 1970's). Right after I graduated from HS in 1972, I also got the midnight-6:00 AM air shift. All through those years, I also teched for several local rock bands.

Anyway, in summer 1972, I asked the station's owner for a raise, since I had worked there for several years, and got....$1.65/hour. At that same time, a position opened in the service department at Driver Music at $2.50/hour, so I turned in my 2 week's notice at KWHP, figuring I was gonna be filthy rich! hehehe From there, I morphed into the recording studio biz.

But, I still had/have a love of All Things Radio. From approx. 1988 to 1994, I did contract engineering work for that same station, then renamed KTNT by the new owners. I would still be there, but the local owner sold the station to one of the mega-groups, who then let most all of the staff go, including the contractors.

Best,

Bri
User avatar
brianroth
Producer
 
Posts: 452
Joined: Sat Nov 07, 2009 1:57 am
Location: Oklahoma City OK

Re: USA AM radio "clear channels"

Postby brianroth » Tue Sep 07, 2010 11:57 pm

Danny,

I'm still looking and I found a couple of interesting articles, but they don't fully explain the science behind directional AM arrays.

http://www.oldradio.com/current/bc_am.htm

(An interesting tidbit in that article is that KFXR 1190 in Dallas, which I knew as KLIF when I was a kid, runs 16 towers, with 4 used in the daytime array, and 12 at night.)

Here's some troubleshooting info, including some of the required VOODOO test gear <g>.

http://www.crawfordbroadcasting.com/~cb ... ooting.pdf

Best,

Bri
User avatar
brianroth
Producer
 
Posts: 452
Joined: Sat Nov 07, 2009 1:57 am
Location: Oklahoma City OK

Re: USA AM radio "clear channels"

Postby dbbubba » Wed Sep 08, 2010 5:36 pm

Hey Brian... the KFXR and former KLIF NIGHT TIME antenna array is about 1 mile from my house!
I can look out the studio door and see the towers.
Look at the website I included below and on the Google map / satellite photo, my house is due south of that array by about a mile or two drags of the satellite image.

The night time array near my house has TWELVE antennas and not sixteen.
The towers are also NOT very tall as far as radio station antennas go.
The "day time" antenna is all the way on the exact other side of Dallas!
The "day time" array has four towers, so they have sixteen total between the two antenna sites.
All sixteen are never on at once (that'd be a HUGE array!)

It is supposedly the most complex antennas array in the U.S. and maybe world according to the website I found about it.
http://wikimapia.org/5271590/KFXR-AM-Ni ... ly-KLIF-AM

Here is some even more technical data on the 12 element array.
Note the plot of the pattern.
http://www.fccinfo.com/CMDProEngine.php ... 1&sHours=N

An interesting side note regarding those towers...
The twelve towers have been a fixture on the northern horizon for me for for sixteen years now.
One night I noticed that they were not all lit!
In fact, only every other tower was lit.
A few days later I drove up to the gate outside the transmitter shack, found the phone number for the owners and gave them a call.
Once I got the proper engineer guy he angrily said, "They are supposed to be that way!"
When I asked why he was still angry and said, "The FCC let's us only light every other tower as a special provision."
I said, "Hey! I was just trying to be nice since we are neighbors and I look at that array every night. I wasn't sure you knew that the towers were un-lit."
What a dink that guy was!
Danny Brown
(I was going call myself Mr. B because I like people to say "MISTER" when they say my name, but then I pitied the fools.)
User avatar
dbbubba
Producer
 
Posts: 773
Joined: Tue Sep 29, 2009 8:44 pm
Location: Rockwall, Texas (Dallas area)

Re: USA AM radio "clear channels"

Postby brianroth » Thu Sep 09, 2010 1:30 am

Danny, yes, I had heard various scuttlebutt about the KLIF array, but hadn't delved into it until this recent foray of mine into AM transmitters and RFI. Their radiated pattern kind of reminds me of the polar pattern of a shotgun mic!

Years ago, I ran across a website that was a TROVE of info about KLIF, but a recent search shows that site is kaput.

Best,

Bri
User avatar
brianroth
Producer
 
Posts: 452
Joined: Sat Nov 07, 2009 1:57 am
Location: Oklahoma City OK

Next

Return to STUDIO LOUNGE

Who is online

Users browsing this forum: No registered users and 1 guest

cron