On 2/6/2021 9:14 PM, Simon wrote:
No yanks on 160m
But mw lively..
1010 interesting..atleast 2 other usa stations competing against WINS..
Shame they don’t announce who they are often..
No make that 3 other stations competing against Wins..
all taking it in turns..
God they like adverts!!
Some general info on AM medium-wave radio in the US:
1) There are approximately 5000 AM stations in the US on about
100 channels. This means an average of 50 stations on every
channel across the US.
2) Legal station IDs are required at the top and bottom of
each hour, although most stations mention their call far more
frequently. The legal IDs are plain voice, while the others each
hour may be dressed up with music, sound effects or not even
mention the legal callsign. The real problem for DXing is that
all the stations on a given channel are giving their legal
plain-language IDs at the same time at :00 and :30 .
3) US (and Canadian) stations are spaced on 10 KHz steps rather
than the 9 KHz steps used in most of the rest of the world. This
results in really nasty heterodynes when trying to DX US stations
from the UK and Europe. Euro carriers land in the middle of
American sidebands and vice versa.
4) US stations range from 500 watt locals in small towns to
50,000 watt long-range monsters.
5) The great majority of US stations go off the air at sundown
local time, to avoid the massive interference from numerous
co-channel stations propagating via long-range sky wave at night.
Or they sharply reduce power at night such as from 10KW day vs 500
w night. The day vs night changes are based on local solar time
and are calculated for the exact location (lat/long) of the
station; they change each month of the year. These are actually
part of the license document. As a result, the "daytimers" as
they are known have a much longer broadcast day in the summer than
in the winter.
6) With some exceptions, the low-power 500-watt - 1KW - 5 KW
local stations mainly populate the upper part of the AM band,
while the high-power 10 KW - 25 KW - 50KW regional stations occupy
the lower part of the band. (Long haul daytime ground wave is
better as lower.freqs.)
7) In the early 1930s, before there were stations in thousands
of small towns, the federal communications authorities created the
"clear channel concept". For a lucky two dozen or so stations, all
but one station on the channel was ordered off the air at night to
produce interference-free long-range reception of a single
high-power station over huge distances in rural areas at night.
Most of these 50,000 watt clear-channel stations were the early
founders of AM broadcasting in the early-to-mid 1920s.
Most of them are distinguished by having 3 letter callsigns
rather than the 4-letter calls that later stations have. I.e. the
"grand old calls" such as WWL (New Orleans), WGN & WLS
(Chicago), WJR & WWJ (Detroit), WSM (Nashville), WLW
(Cincinati), KSL (Salt Lake City), KOA (Denver), KFI (Los
Angeles), etc. With a few exceptions, calls beginning with "W"
are east of the Mississippi River (which roughly divides the
continental US in half), while calls west of the Mississippi begin
8) Most of the stations that started broadcasting in the 1920s
and 1930s (i.e. the early entrants) have non-directional antenna
patterns from a single 1/4-wave stick. Later arrivals to the
ever-more-crowded AM band have been obligated to protect the
coverage of existing stations on each channel. This usually has
meant multi-tower directional antenna patterns for the
new-comers. The most common directional array is three phased
towers in a straight line. (Broadcast antenna arrays almost
always drive all elements, rather than have passive elements like
HF yagis.) Some arrays can get very complex. For example, there
is one station in Detroit, Michigan that has 11 towers in two rows
that create a weird amoeba-like pattern with multiple lobes and
nulls in various directions to protect stations in Ohio, Indiana
and Ontario, Canada.
A lot of stations run higher power with a non-directional antenna
in the daytime, and then switch to lower power and a directional
pattern at night.
For you DXers from the other side of the Atlantic, this is
significant. When the grey line reaches a given location (i.e.
sunset), the signal from a particular station can actually
instantly disappear or appear, depending on the day vs night
pattern and power level changes.
9) The most powerful AM stations in the US run 50,000 watts.
In the mid 1930s one station (WLW north of Cincinnati, OH) was
allowed to experiment with 500,000 watts for a few years. This was
the most powerful AM station that has ever existed in the United
States. [There were several 500KW "border blasters" operating
from Mexico, but directed to audiences in the US about the same
A few years later, the US government tapped the engineering
expertise of Crosley Broadcasting (owners of WLW) to build
multiple 500 KW shortwave transmitters with monster rhombic
antennas to beam news into Germany during WWII. This site, about
a mile west of WLW's site, consumed so much electricity that it
was connected to both the City of Cincinnati power grid to the
south, and to the City of Dayton grid to the north at the same
time! In the post-war era, this facility became one of only
three Voice of America transmitters actually on American soil.
The Bethany, Ohio VOA site was decommissioned about 20 years ago,
and converted into a museum. If you ever visit the Dayton
Hamvention, don't miss this museum which is about a 45-minute
drive south down I-75 from the Hamvention site. They keep the
museum open for special extended hours during the Hamvention. The
museum ham club has re-created some of the rhombics from the VOA
era and has a commanding signal on the HF bands.
Stephen H. Smith wa8lmf (at) aol.com
EchoLink: Node # 14400 [Think bottom of the 2-meter band]
Home Page: http://wa8lmf.net
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