David Eduardo wrote:


"Brenda Ann" wrote in message
...

"RJ" wrote in message
...
I live in NE Penna, and one of my favorite
nighttime MWDX's was WCCO in Minneapolis. ( 830 )

Recently, the signal is completely blocked
by a signal from Reading Pa. also broadcasting on 830.

I thought that WCCO was a "clear channel" station.

Maybe I misunderstood the meaning of "clear channel"
I thought they were all hi-powered stations,
and if they did share a frequency, it was because
they were a couple thousand miles apart.

Can someone enlighten me ?


There are no more "clear channel" stations, haven't been for some time.
The
FCC has been issuing licenses for low power and/or directional facilities
on
the former clear channel frequencies.

Still, the dominant stations on the clear channels are called clear channel
stations as their signals are protected day and night against interference.
All other stations on the channels are far away, and if night operations,
they protect the cominant station. All the former 1-A and 1-B clears operate
with 50 kw at night except for 1560 in Bakersfield and 1190 in Guadalajara,
both of which have 10 kw at night.

The real change is that the need for the kkind of national coverage the 1-A
clears touted in the late 40's is no longer there. Very few people listen to
station from outside thier market any more, and they are nt well disposed to
putting up with fading, interference, static and all the other pleasures of
AM distant reception.

At one time, there were hundreds of thousands of AM DXers in the US...
newspapers had DX columns...and a wide variety of high quality receivers was
on the market. Today, maybe there are a thousand AM DXers and the intereest
in distant reception is for all practical purposes dead.

That's because radio is so common now. In the 1920s, when radio was just
being born as a commercial medium, most people lived in small towns
which were very unlikely to have their own broadcast stations. The
nearest station was likely to be in the nearest "city" (more like a
medium sized town by today's standards) which could be a couple hundred
miles away. The broadcast band was wide open for what stations did
exist. "Clear channels" were exactly as the name implies-stations that
had to be in the clear to serve dozens of little farm towns within a
radius of several hundred miles. in the 1940s this situation still
applied. But as people moved off the farm and into the city after WW2,
the need for clear channel stations disappeared. Stations which once
broadcast news and entertainment to farms refocused on their local
markets. And then came TV in the 50s which took away AM's traditional
news and entertainment schedule, and then FM in the late 60s which took
away the music market, and you have today's AM band-right wing talk,
sports, and ethnic programs. The same thing is happening to SW in
Latinoamerica and Africa-FM is taking over SW's traditional functions as
people are being forced out of the jungles and deserts and into the
cities.