Listened to some Colorado radio this morning - in TX

[Cliffh]

Driving to work this morning I was listening to the local talk show on AM.  For some unknown reason, the radio changed from the 820 freq its normally on to 850.  I didn't notice the change because it happened during the commercial/news/traffic period. 

What got my attention was when they started talking about the traffic going through a tunnel.  There aren't any tunnels around here??  Then they started talking about how this & that was happening (locally) in Colorado. 

I live in N. Texas.

It was kinda weird. 

That AM signal bounced - a lot.

[RocketMan]

Probably KOA 850 AM in Denver.  They have a strong clear channel signal that can be heard a long way out of state.

From the Wikipedia entry on Clear Channel AM stations:

A clear-channel station is an AM radio station in North America that has the highest protection from interference from other stations, particularly concerning night-time skywave propagation. The system exists to ensure the viability of cross-country or cross-continent radio service enforced through a series of treaties and statutory laws. Known as Class A stations since 1982, they are occasionally still referred to by their former classifications of Class I-A (the highest classification), Class I-B (the next highest class), or Class I-N (for stations in Alaska too far away to cause interference to the primary clear-channel stations in the lower 48 states). The term "clear-channel" is used most often in the context of North America and the Caribbean, where the concept originated.

Since 1941, these stations have been required to maintain an effective radiated power of at least 10,000 watts to retain their status. Nearly all such stations in the United States, Canada and The Bahamas broadcast at 50,000 watts, ...

[230RN]

Radio probably auto switched to the stonger frequency during a dip in the weaker one's signal.

Northeast Texas to Denver is kind of a stretch, but not impossible to be getting a direct wave.  Panhandle of Texas not unlikely.

Just guessing, but the mountains could be partly channeling or reflecting the signals. 

Eight-fifty kHz is a pretty long wave.  For a mental touchpoint, 1000 kHz ( one mHz) is a 300 meter wavelength signal. Eight-fifty is 353 meters.*

Why, that's almost DC  (Direct Current) ! !

^ Ham joke.  They used to call the 160-meter ham band "the DC band" because it was "only" 1.8 mHz compared to the higher frequencies of the other ham bands. ROFL

Terry, 230RN

* wavelength =  speed of light / frequency

As the frequency gets higher, the wavelength gets shorter.

[Cliffh]

That's my "one new thing" learned for today.  And interesting to boot!   

If I can remember, I'll try tuning to 850 tomorrow.



I'm closer to Louisiana than the TX Panhandle.  This happened at ~0640 CT.

[zxcvbob]

IIRC, AM 820, WBAP, is also a clear channel station, broadcasting at 50kW.  (I used to listen to Bill Mack's late night trucking show.  It should easily be a stronger signal in Texas than KOA, and they are not that close together on the band.   Maybe they went off the air due to technical difficulties (a tube went out )  But more likely the radio just did a scan for some reason and found the next strong station. 

I also used to listen to 870 WWL in New Orleans and 650 WSM in Nashville.  I don't remember the clear channel stations in San Antonio (was it WOAI?) and Chicago; it's been too long since I listened to AM.  XERF just across the border in Mexico used to claim to broadcast at 1MW but I think it was actually about half that but they had a directional antenna aimed at the US. (Wolfman Jack got his start there)

[Tuco]

Bill Randall 650 Dorothy S. Ma'm
The Axlewide and Peppermint Endurance Company in Bashful Johnny C
Home of the Grand Ol' Conglomeration, Fannie Hill University and the Bathtub of the South.
It's 7:30.

[230RN]

zxcvbob said,

"But more likely the radio just did a scan for some reason and found the next strong station."

That's what I said above. OP probably drove through a dip* in the weaker station's signal and the radio captured the stronger one with its automatic tuning.

Terry, 230RN

* Due to any number of things, some weird reflection, local change of polarization of the signal, blockage by some object (truck, building, advertising sign), interference by its own skywave  (~0640 CT), et, as they say, cetera.

Edited to correct "zxcvbpb."

[K Frame]

Those atmospheric skips are pretty neat. I could occasionally get Detroit and French Canada stations when I lived at home outside of Harrisburg, Pennsylvania.

One early evening pretty much the entirety of the US east of the Mississippi was socked in with a damp, foggy, low level weather system.

The town fire siren went off. Dad goes flying out the door wondering what was going on because his scanner had been silent.

Town volunteer fire department gathers and... they're all very confused. They called the local dispatch, and nope, no calls for our town, no indication on their equipment that the radio activation of the town signal had come from them.

Turns into something of an investigation to see if there's some unknown fault in the systems, and there isn't. It was an atmospheric skip from Jackson, Mississippi.

[RoadKingLarry]

Back in the '70s my favorite radio station was KVOO 1170AM out of Tulsa. 50KW station. For whatever reason they would shift their antenna pattern at 5:15 PM every day and reception at our house went to crap but it worked to my benefit.
Mom's car was a 1974 Opel Manta. Dad had installed some kind of aftermarket electronic ignition on it after the OEM ignition had failed. That ignition generated enough RF noise I could hear her coming 1/4 mile away over a quiet AM radio freq. Kind of a "early warning system" for the imminent arrival of the menopausal monster. 

[RocketMan]

Many years ago I participated in Kangaroo II, at the time the largest USMC amphibious landing exercise in Australia since WWII.  My battalion shipped out of Pearl Harbor aboard the USS San Bernadino, a LST.  The Navy would often ask for Marine radio operators to help out in the LST radio room when we were aboard ship.  I volunteered for that duty because it sounded interesting.
One slow evening way out in the Pacific ocean, near Kwajalein Atoll if I am remembering our position correctly, I fired up an R-390A receiver just to see what I could pick up.  Among other stuff I heard KEX 1190 out of Portland, OR.  They were quite clear.
Thinking about that event years later, it didn't surprise me too much as they are a clear channel 50kw station with a three bay antenna beaming to the southwest.
Speaking of R-390A receivers, I have one that I need to restore.  It worked when I first got it years ago, but didn't the last time I fired it up.  Probably a failed tube.

[K Frame]

"Many years ago I participated in Kangaroo II,"

Is that racist? That feels racist to me. Are you a racist to the upsidedown continent? 

During World War II ships in the US ships in the Pacific would communicate using a very low powered, I THINK, UHF radio at night or in really bad visibility weather. Basically it wasn't supposed to travel more than a couple of miles.

They largely quit using it after after they started getting regular reports from Pearl Harbor that it could monitor ships in the Central and South Pacific, several thousand miles away.

[230RN]

"Probably a failed tube."

For someone without a tube tester, with the set off and cold, pull the tubes and re-insert them one at a time so you don't mix up what tube went where.

Then try the set again.

P = ~0.20 that that trick will do the trick.

[Cliffh]

 Yesterday wasn't a fluke.  Tuned the radio to 850 this morning, KOA Denver came in quite clear for a few miles.  Once I got into town the power lines caused too much noise.

I've got it on a preset now.

I tried it again as I left work this afternoon - about 10 miles from where the signal was clear this morning, and in the middle of a larger town - all that came in was a Mexican music channel.

[RocketMan]

"Many years ago I participated in Kangaroo II,"

Is that racist? That feels racist to me. Are you a racist to the upsidedown continent? 

All I know is that I had to hold on tight to keep from falling off the world when I was walking around down there.

[Andiron]

https://www.songfacts.com/facts/zz-top/heard-it-on-the-x

https://youtu.be/7L7ew003rBg

[JTHunter]

KMOX Radio 1120 in St. Louis keeps touting their "50,000 watt blowtorch" with a "clear channel".  I have had their signal bounce down to central Florida back in '03 when I was on vacation down there.