largest city with no AM transmitter?

[Dan.Strassberg]

The answer lies in geography--and history. On the East and West
coasts, most of what used to be Class II and III AMs (now Class Bs)
directionalize out over the oceans (or in the Gulf coast states, over
the Carribean). For older stations, this meant that relatively simple
arrays (usually three--or even two--towers) would do the trick. In the
northern Midwest, older stations would directionalize to the north
because Canada didn't have many stations and the use of the channels
was first-come first-serve. But as the AM band became more and more
crowded, the protections became more and more difficult to achieve, so
as time went by, stations that wanted to upgrade their signals were
allowed to deliver their strongest signals over narrower and narrower
arcs.

1130 is the most-often-cited example of how complex arrays allowed
shoehorning of relatively high-powered stations onto a channel's
remaining "open space." Like many of the former IB channels, 1130 is
home to two US Class A stations; one in New York City and one in
Shreveport LA. However, unlike 710, with Class As in New York and
Seattle, 1080 (Hartford and Dallas), 1110 (Charlotte and Omaha), 1170
(Wheeling WV and Tulsa), 1500 (Washington DC and St Paul MN), 1510
(Nashville and Spokane), 1530 (Cincinnati and Sacramento), and 1560
(New York City and Bakersfield CA), the Class As on 1130 have patterns
that don't exactly face away from each other. The reason for this
situation is that there is a third legacy Class A on 1130 in North
America, CKWX, Vancouver BC. KWKH must protect both WBBR and CKWX, so
its pattern is aimed pretty much to the south, whereas WBBR aims
more-or-less east and CKWX aims northwest. Each of these three
stations thereby protects the other two at night, leaving an open
space in the midwest that is filled by three stations (in Detroit,
Milwaukee, and Minneapolis), each with a nine-tower array and night
power of 10 kW or more. The very similar, very narrow, nine-tower
patterns are tear-drops (also called flashlight or searchlight
patterns) aimed to the north or northeast to protect WBBR, KWKH, and
CKWX.

WXYT, which you mentioned, is a very old station that ran 5 kW-U DA-N
until a few years ago. The night pattern was a two-tower modified
cardioid aimed east. My understanding is that WXYT's management
decided that WXYT HAD to increase to 50 kW to compete for sports
play-by-play rights because the Detroit area already had several 50 kW
AMs and the teams had decided that they were in a position to insist
that any AM that wanted to carry their broadcasts had to run 50 kW-U.
CBS, which I believe owns or owned WXYT, got what it wanted: 50 kW-U,
using a very unconventional nine-tower array of modern design. The
problem is that, for the most part, WXYT's signal is worse now than it
was with 5 kW. First of all, the old 5-kW facility used tall, and
hence highly efficient towers. Because of the narrow patterns required
to meet FCC protection requirements, the signal improvement occured
only over a narrow arc to the north--and even there, I've been told,
WXYT's signal suffers from severe phasing (fading) because of the
strong high-angle skywave that results from using very short towers--a
zoning requirement imposed by the community in which the array is
located. So WXYT got 50 kW and got at least the Tigers play-by-play,
but after spending millions on land and equipment, it now has a poorer
signal--pretty much everywhere--than it did for all those years as a 5
kW station. This story shows how stupid team management, with
cooperation from arguably stupid station management, created a
situation in which nearly everybody lost--although WXYT does derive
big profits from those sports broadcasts.

-----
Dan Strassberg (dan.strassberg@att.net)
eFax 1-707-215-6367

----- Original Message ----- 
From: "Kevin Vahey" <kvahey@gmail.com>
To: "Dan.Strassberg" <dan.strassberg@att.net>
Cc: "Boston Radio Interest"
<boston-radio-interest@rolinin.bostonradio.org>
Sent: Friday, September 14, 2007 4:48 PM
Subject: Re: largest city with no AM transmitter?


>I have always wondered why Detroit has the directional signals they
>do
>  WXYT ( the former WXYZ ) should have had a better signal than it
> was
> given
>
>
>
> On 9/13/07, Dan.Strassberg <dan.strassberg@att.net> wrote:
> Detroit is the complex-array capital of North America
>> (with Toronto a close second) and it's REALLY tough to find land
>> for
>> eight-, nine-, and ten-tower arrays in major cities.