Mark Keith wrote:
Yup...Thats what I use. You know it's up to date..Most of my books are
getting old and miss many new stations in the upper end of the band.
Also, you see exact location, power, who owns it, "does Clear Channel
own them all now? :/ Almost seems like it... " You can also tab over
and look at their site and antenna data. I see some of the new
stations are running newer "weird" power levels for MW. IE: I have
seen some with real super low power, "in the past 250w was kind of the
standard low end rating" and then oddball ratings like maybe 31 KW or
whatever for some...It seems the "standard" 250,500,1K, 5k,10k,50k
ratings are kind of going out the window in many cases of the new
stations. MK

Yep, the regulation that limited stations to specific power levels was
repealed some time ago. I'm not too sure why it existed in the first
place - maybe because they wanted transmitters to be type accepted at
each specific power at which they would be used?

250 watts is still pretty much the lower limit, with a couple of exceptions:

- When a station that used to be authorized for 250 watts installs a
taller tower[0], and needs to reduce power to keep from interfering with
other stations.

- Stations that used to be authorized for daytime operation only.
(before the specific-levels regulation was repealed, if a station
couldn't run at least 250 watts at night without interfering, it
received a daytime-only license. When the regulation was repealed, the
FCC, on its own motion, calculated how much power each station could run
without interfering and issued nighttime permits for that power level.
For some stations that level could be as little as one watt! Operation
at these low powers is secondary - not protected from interference - and
not mandatory - it doesn't count for compliance with the minimum
operating schedule regulations.)

- Stations that used to be authorized for fulltime operation at higher
powers but chose to convert to Class D. Usually this means the station
used to operate non-directional during the day, directional at night,
and for some reason decided to take down the extra towers and go
non-directional fulltime.[1] Going non-directional requires that the
station radiate no more power overall than it used to radiate in the
direction of least radiation when it was directional. This again could
be as little as one watt! - but usually is on the order of a few dozen.
If the figure is less than 250 watts, the station becomes Class D.

- Stations that were authorized for lower powers under earlier
regulations, and never bothered to increase power when blanket increases
were offered. I believe WMAM-570 in Wisconsin (250 day, 100 night) and
WSAJ-1340 Pennsylvania (100 watts specified hours) are the only two
remaining such stations.

[0] A taller tower may be more efficient - may radiate more signal for a
given number of watts.

Usually when a smaller AM station installs a taller tower, it's to
increase the coverage of an associated *FM* station whose antenna is on
the AM tower.

[1] Often, AM transmitter sites in what was once rural swampland have
become valuable potential subdivisions in suburbia. It's not unusual
for the land under the towers to be worth more than the entire station,
including the intangible value of the license.
--
Doug Smith W9WI
Pleasant View (Nashville), TN EM66
http://www.w9wi.com