"Antonio" wrote in message
...
I always have wanted to know how much power are stations allowed to
operate.
I remember while living in Mexico, listening to XEWA 540AM, they used
to operate at 150,000 watts day and night, but now they are less than
that, probably 5000 watts or something.

150,000 day and night.

XEW 900 is well known, they use 250,000 watts and say they cover most
of North America.

They say nothing like that. The signal had been dropped to 100 kw for many
years, but due to high man made interference in Mexico City, they upped it
again to provide good coverage of the Mexico City metro area.

American stations use at most 50,000 watts and they are forced to
lower their power at night,

Some US 50's are 50 day and night; a few are non-directional all hours,
others go directional at night, others are directional at all hours. And
then there are many 50's in the daytime, that reduce to lower levels at
night... as low as 250 watts!

while at the same time, one station, I
think is in Mexico City, goes from 5,000 to 150,000 at nights.

Not so. In the 60's, XERF in Cd. Acuña, Coah., on 1570 only operated at
night as it's business was mail order and preachers. This was an exception.
It is now 15 kw day and night.

No Mexico City AM has higher night power than day power.

Any explanation would be appreciated and one question,
Is there any pros and cons of running that much power?
How about other countries, whats the most power a station can have?

Mexico: 250 KW. Most of Central America: 50 kw.
Colombia: 250 kw
Venezuela: 1,000,000 watts.
Chile, Argentina: 100 kw

Many European nations have 1,000,000 stations. Higher power is used in
several of the Arab nations.

David Eduardo wrote:

Some US 50's are 50 day and night; a few are non-directional all hours,
others go directional at night, others are directional at all hours. And
then there are many 50's in the daytime, that reduce to lower levels at
night... as low as 250 watts!

KIQN/Tooele UT on 1010 runs 50,000w day, 3,100w critical hours and a
whopping 13w (yes thirteen watts) nights.

"David Eduardo" wrote in message ...
"Antonio" wrote in message
...
I always have wanted to know how much power are stations allowed to
operate.
I remember while living in Mexico, listening to XEWA 540AM, they used
to operate at 150,000 watts day and night, but now they are less than
that, probably 5000 watts or something.

150,000 day and night.

XEW 900 is well known, they use 250,000 watts and say they cover most
of North America.

They say nothing like that. The signal had been dropped to 100 kw for many
years, but due to high man made interference in Mexico City, they upped it
again to provide good coverage of the Mexico City metro area.

XEW 900 is listed at the Secretaria de Comunicaciones y
Transportes(www.sct.gob.mx) with 250 kW, along with other 3 more
stations with more than 50 kW(XEB 1220 100 kW, XEEP 1060 100kW, XEX
730 100kW). I remember listening to XEG 1050 from Monterrey, the
signal sounded better than some locals and but only at nights.
Its a shame that the Secreataria doesnt provide coverage maps for the
stations, it would be nice to see a coverage map for a 100kW or a
250kW.
Is there a way to make a map with the Effective Radiated Power, Height
above Avg. Terrain and Antenna Pattern?
XEW 900 broadcast over the Internet at www.esmas.com/wradio. The site
used to stream a few other FM radios, it dropped them and now only has
W Radio and other Pop station.
The promos of XEWA 540 used to say the covered North Mexico and the
South of the USA, and they fed their signal to regular satelite, you
could hear either a Televisa channel or the station. Satelite radio?

There was talk some years ago of a 5 or 6 million watt AM in Egypt.
Not sure if it ever happened.
--
Gene Seibel
Broadcasting page - http://pad39a.com/gene/broadcast.html
Because I fly, I envy no one.


"Antonio" wrote in message
...
I always have wanted to know how much power are stations allowed to
operate.
I remember while living in Mexico, listening to XEWA 540AM, they
used
to operate at 150,000 watts day and night, but now they are less
than
that, probably 5000 watts or something.
XEW 900 is well known, they use 250,000 watts and say they cover
most
of North America.
American stations use at most 50,000 watts and they are forced to
lower their power at night, while at the same time, one station, I
think is in Mexico City, goes from 5,000 to 150,000 at nights.
Any explanation would be appreciated and one question,
Is there any pros and cons of running that much power?
How about other countries, whats the most power a station can have?

Are there still clear channel stations in the U.S? I thought they dropped
that years ago.

scott


"Peter H." wrote in message
...


I always have wanted to know how much power are stations allowed to
operate.


This is specified by international treaties. For North America, this would
be
the North America Regional Broadcast Agreement (signed 1939, effective
1941),
and the subsequent U.S.-Mexico Broadcast Agreement and U.S.-Canada
Broadcast
Agreement.

For Class I-A stations, only, the wording was stated to be "at least
50,000
watts" because Mexico was already using in excess of 50,000 watts.

For all other Class I-B and Class II-B stations the wording was stated to
be
"50,000 watts".

However, Mexico subsequently authorized 100,000 watts, during daytime
only, for
stations not otherwise entitled by treaty to use more than 50,000 watts.

In fact, for some stations which were limited by treaty to 10,000 watts,
Mexico
also allows 100,000 watts, during daytime only.

The much later "Rio" treaty further modified the rules, and allowed for
the
first time Mexican and Canadian operations on U.S. clear channels, as well
as
unrestricted operation of U.S. stations on Mexican clears.

(The earlier NARBA treaty had already authorized U.S. operations on
Canadian
clears, provided the stations were more than 650 miles from the
U.S.-Canadian
border).


I remember while living in Mexico, listening to XEWA 540AM, they used to
operate at 150,000 watts day and night, but now they are less than that,
probably 5000 watts or something.


XEWA was not the original Class I-A occupant of 540.

By 1941's NARBA, 540 was given to Canada as a Class I-A.

By the mid-1950s U.S.-Mexico agreement, 540 was added to Mexico's Class
I-A
list, and that frequency was assigned to San Luis Potosi, at 150,000
watts.

IIRC, XEWA is still operating with 150,000 watts.

Certainly, it is "notified" and authorized to do so.



XEW 900 is well known, they use 250,000 watts and say they cover most of
North
America.


NARBA also gave the U.S. night time priority on 800 and 900 in Alaska,
although
one of those stations has been changed to a U.S. clear channel on account
of
excessive interference from Canada.

Insofar as the U.S.-Mexican treaty, the U.S. includes all states and
territories, so Hawaii, Alaska and P.R. are included, even though these
states
and territories really can't interfere with Mexico's "notified"
operations.

However, Canada, not being contiguous with Mexico, used all Mexican clears
for
whatever purpose it wanted. It's just that Canada could not "notify" any
Class
I stations on those frequencies.

Additionally, the U.S.-Mexican treaty prohibited the U.S. from operating
any
station on Mexican clears at night, and also prevented any day operations
greater than 1 kW. Unless specifically excepted by treaty, which covered
the
50,000 watt DA-1 operations in Cleveland (1220) and New York (1050), and
the
5,000 watt operation in Alaska (800 and 900).



American stations use at most 50,000 watts and they are forced to lower
their
power at night, while at the same time, one station, I think is in Mexico
City,
goes from 5,000 to 150,000 at nights.


U.S., Canada and The Bahamas have a 50,000 watt limit.

Unless a specific station is "notified" for lower power at night, the same
power may be used night as well as day.

Class I-A and I-B (now Class A) stations are permitted a flat 50,000 watts
(more for Mexico, under the conditions described above).

That is, unless the Class A is "grandfathered" at a lower power, say,
10,000
watts.

There is only one U.S. Class A station which is so grandfathered.

There is one Canadian stations which is so grandfathered (1550).

There are three Mexican stations which are so grandfathered (1000, 1190
and
1550).



Any explanation would be appreciated and one question, Is there any pros
and
cons of running that much power?


Lots of power was needed to cover "underserved" areas in decades past.

Lots of power is now needed in order to overcome all the man-made
interference
from the gazillions of switching power supplies used in computers and
entertainment appliances.

With "Rio" stations which were formerly limited to 5,000 watts were
allowed to
increase to 50,000 watts.

Practically speaking, this only applies to "historical" Class III-A
stations
(KJR, KMJ, KKOL, KXTA, etcetera, etcetera, etcetera) as these Class III-A
stations received better protection then Class III stations of inferior
priority (Class III-B, e.g.).



How about other countries, whats the most power a station can have?


In Europe, there is/was a 1,400,000 watt station.

But, because of unauthorized use by other countries (Cypress and Israel,
IIRC)
the 1,400,000 watts is largely wasted at night.

Are there still clear channel stations in the U.S?


There are still clear channels ... just no clear channel stations.

There are NO channels assigned to the highest priority station which are no
duplicated by statons of lesser priority.

Are there still clear channel stations in the U.S? I thought they dropped
that years ago.

As the term "clear channel" was originally defined (meaning, only one station
on the frequency across North America), yes...that was dropped decades ago.
IIRC, WLW was the last one.

In Europe some AM stations have 1,000 kw, more on longwave.

Mike

"Geoff Brozny" wrote in message
...

I saw in the FCC's database a station in cuba that was at 500kw, this link
will show you all the stations in the western hemisphere.

http://www.fcc.gov/fcc-bin/amq?state...0&fre2=1700&fa
cid=&list=0&dist=&dlat2=&mlat2=&slat2=&NS=N&dlon2= &mlon2=&slon2=&EW=W&size=1
0

geoff

I believe that the Cuban 500 kw station is on 710 kHz. This is part of
Castro's "radio war", to keep Miami's Spanish speaking Radio Mambi (710
also) from reaching the island.

In article , says...

"Antonio" wrote in message
...
American stations use at most 50,000 watts and they are forced to
lower their power at night,

depends on what class AM station they are, for example 700WLW is a class A
AM station with unlimited hrs of operation, so they are 50kw 24/7.

while at the same time, one station, I
think is in Mexico City, goes from 5,000 to 150,000 at nights.
Any explanation would be appreciated and one question,
Is there any pros and cons of running that much power?

at night the station would carry real far, and could possibly interfear with
other stations real far away, and I guess you could say another con would
be you could have less stations on that same frequency.

How about other countries, whats the most power a station can have?

I saw in the FCC's database a station in cuba that was at 500kw, this link
will show you all the stations in the western hemisphere.
http://www.fcc.gov/fcc-bin/amq?state...=&EW=W&size=10

geoff















Nobody has mentioned that for 5-years of so back in the 1930's WLW
was licensed for 500,000 watts. The signal was so strong that
florescent bulbs within a few miles of the transmitter would glow, and
the station had to cut daytime power to 50,000 watts until "directional
suppressor towers" because the signal interfered with a station in
Toronto.
The whole story is on Jim Hawkin's WLW page, including other
interesting facts, pictures and schematics of the WLW transmitter site.
( http://www.hawkins.pair.com/wlw.shtml )
It doesn't mention it on this site, but I believe the station had
daytime listeners through most of the 48-states, and was heard in Hawaii
and Europe at night.


--
Paul Van House
(remove _removeme_ from mail address for e-mail replies)
Radio/TV Software on my home page
http://www.binxsoftware.com
Coming Soon: A Voice For You (Voiceovers, Liners, On-Hold Imaging)
http://www.avoiceforyou.com