Why does KBLA 1580 have a better signal in American Samoa than Pacoima? Does it have to do with the antenna? Thanks to anyone who can answer this. (I'm trying to learn about the technology without being too disruptive). Thank you.
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What If AM Radio Was Discontinued?
- Thread starter blackgold
- Start date
Yes. This was a common strategy to shoehorn stations into coastal cities. Place the antenna site inland, and build a directional antenna to beam all the power out to sea. It basically meant there could be a high power (50kW days) station on 1580 in LA without interfering with the 1580 in Phoenix or Salem, Ore.
Oldies 919, Radio has changed so much since the late1970s and early 1980s. Since then the number of radio stations has tripled. There are many places to spend your advertising budget today. I was at a station doing about $30,000 in 1981 that in 1993 could barely do $16,000 not accounting for inflation. Another AM was commanding $36,500 for a lease in 2007 but couldn't get more than $20,000 with a vastly improved signal in 2019. At the station where I am, one account I have used to spend $1,200 a month in the 1980s but now they spend $300 and it was a struggle to get that. My point is what was possible then is certainly not now unless by exception. Not only is it the ad dollars, the listening audience is now split among triple the stations. You won't see stations dominating the dial like you did then because of the listening choices. Then there's the increased noise level on AM that has listening down to 5-15% of radio listeners.
The station transmits
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It did not specifically protect XEDM. It protected the Mexican border everywhere, as 1580 is a clear channel shared between the United Mexican States and Canada. US stations on 1580 are limited to protecting the entire border. In theory, another Mexican use of 1580 could occur, and not necessarily in Hermosillo. In that case, KBLA would still be protecting the Mexican station no matter where it was.
Thank you, exbloguero !
The protection on 1580 was mostly for the Mexican and Canadian borders. Daytime it protected Mexico as well as stations on 1570 and 1590.
Santa Monica on 1580 dates back to 1949 as a 5 kw daytimer, long before Tempe or Salem came on the air. It increased to 10 kw, still daytime, in the early 50's and by 1960 it was 50 kw, still daytime. By 1970, they had a CP for night operation with separate patters day and night.
Tempe did not hit the air until 1967, and did not get night operation on the air till the later 70's. There was nothing in Oregon on 1580 even as late as 1970, well after KDAY got its night CP.
A good example of the extremely high conductivity of salt water can be seen if you are on an island coast.
I spent quite a few decades in Puerto Rico, and would often take vacations on the SW coast around Guánica. At that location, even 1 kw stations from coastal Venezuela were listenable, and some of the 10 kw or higher ones boomed in. So did the stations from Aruba and Curacao and even more distant Trinidad as well as coastal Colombia. Those were distances of over 600 miles, with Barranquilla over 725 miles.
Yet 10 kw stations from San Juan, less than 90 miles away but over land, could not be heard at all.
Interestingly, at that location stations to the west from the nearby Dominican Republic were not easy to hear, nor were others that were directly to the east or west.
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Not always. Take Vashon Island as an example: The ground underneath the AM stations is terrible, as in non-conductive, so a station located at one end of the island has reduced groundwave toward the other. KVI is a prime example, being located far end to the South, so it's signal suffers North toward Shoreline and Everett.
Or a ship. While deployed to SE Asia in the 60's my destroyer could reach San Francisco reliably on code or RTTY (500 watts AM and/or SSB). We had nothing but problems getting into Japan, Guam, Kwajalein etc.
I don't know if the writers of Gilligan's Island knew that, but that is how the castaways' AM radio was able to pick up stations on that distant island in the daytime.
You can't be serious.
Just trying to make sense of that otherwise silly situation.
"As late as 1970" is interesting phrasing. 1580 hit the airwaves in 1995, licensed to Lebanon Or, at least 30 miles from Salem and I doubt if it goes there very well, if at all! Think Corvallis(Oregon State University)/Albany and Corvallis is iffy.
But, it was a TV show. Do you think writers take into account things like radio signals? 99.98% of humans already don't.
I remember seeing a movie called "High Frequency" on HBO back in the '80s. It involved a young radio amateur in Maine who somehow contacts another ham at a satellite relay station somewhere in the Alps and gets involved in a murder mystery. The real mystery is how the contact was made. In the film, it is the middle of the day in Maine and the frequency the two stations are communicating on is -- and my memory is fuzzy on this -- somewhere below the amateur 80-meter band, I believe around 3200 KHz. There is no propagation between the East Coast and Europe on that frequency (or the legitimate ham band above it) at that time of day, but no one but radio nerds was ever going to notice the incongruity.
NOTE: Just corrected 3200 MHz to 3200 KHz. Oopsie!
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Fast forwarding to now; your cell phone is nothing more than a type of radio. A radio that works 90% of the time, no matter what town, or even country. And yet, your average consumer still doesn't give it a single brain cell of thought.
My wife really likes Deadliest Catch on Discovery. I find it puzzling how these crab boat captains can call each other via cell phones out in the middle of the Bearing Sea, even near the Russian border. The answer is: they can't. The producer's don't want to show them using clunky sat phones with dropped connections, or noisy VHF radios, so they stage the cell phone conversations.
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