WLIB and WXLX

[Dan Strassberg <dan.strassberg@worldnet.att.net>]

I'm taking the liberty of posting this both to Airwaves and the Boston Radio
Interest Group because it is of interest to both audiences.

Unless I've stumbled across an error in the AM
database (what? an _error_ in the database?
couldn't happen! could it? :-), I think I've
discovered one of the things that is holding up
WLIB's move to fulltime and is allowing the
_real_ WOWO to survive a little longer. WLIB and
WXLX are apparently planning to operate from the
same site, which appears to be WLIB's existing
site.

WLIB's current day array comprises three
172-degree towers spaced 106 degrees apart olong
a 100-degree line. The new night array will use
the center and east towers of the existing array
plus two new towers, not quite in line with the
existing ones (110-degree line) and just a little
shorter (165.5 degrees). The two new towers will
be quite close to each other (65.8 degrees) but
will be quite a way east of the old ones. The
distance from the existing east tower to the
first new tower is 142 degrees.

One of the three old towers will be the center
tower of the WXLX array, which comprises five
towers, all used day and night. The towers are in
line, 90 degrees apart, on a 128-degree heading.
WXLX's four new towers will be shorter than the
center tower. The center tower works out to be 91
degrees at 620, whereas the new towers will be 68
degrees.

When the construction is complete, there will be
nine towers at the site, some of which will be
very close to each other. Of these, five will
belong to WLIB, which will use three during the
day and four at night, four will belong to WXLX,
and one will be shared by the two stations. Of
the nine towers, six will be new.

A true curiosity is that BOTH stations will be
using higher power at night than during the day.
WLIB will be 10 kW-D/30 kW-N, as you know, and
WXLX will be 3 kW-D/7.6 kW-N. Also, WLIB's night
pattern has a pronounced null to the northeast.
The null seems too far north to have been
designed to protect the old CHTN on 1190. At the
moment, though, the only reason I can think of
for WLIB to null to the northeast (actually, the
north-northeast) is that the engineering work was
done before CHTN moved to 720 and ICBC was too
cheap to have it done over again.

Another factor that could be causing the
engineers fits is the close proximity of the site
to WOR, WEVD, and WBBR. According to the
database, they are all within about 1 km of the
WLIB site. At night, there will be almost as much
RF there as there was south of the WLW site when
WLW was running 500 kW (directional, yet--to
protect CBF).

On a related but unrelated note (another station
with higher power at night than during the day),
the database shows a radiation peak for WWJ's
proposed 50 kW night operation of almost 10V/m
unattenuated at 1 km. Yes, folks, that's VOLTS/m!
If my calculations are right, that's the
equivalent of around 1.25 megawatts
(yes--megawatts) nondirectional from an antenna
having the minimum allowable efficiency for a
Class III AM. If the data is correct (and I
question it), that has got to be the strongest
signal of any AM in North America. One problem is
that the antenna efficiency appears to exceed by
a comfortable amount the maximum possible from
5/8-wave towers, and the towers, which are of two
different heights, are all less than half wave.

- -------------------------------
Dan Strassberg (Note: Address is CASE SENSITIVE!)
ALL _LOWER_ CASE!!!--> dan.strassberg@worldnet.att.net
(617) 558-4205; Fax (617) 928-4205

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