WITS/Red Sox

Dan Strassberg dan.strassberg@att.net
Sat Oct 7 17:26:15 EDT 2006

WUNR uses the same two-tower directional pattern day and night. The towers
are spaced 105 degrees apart along an axis at 70 degrees. As you observed,
the towers are quite tall--greater than half wave--205 degrees to be
precise. Consequently, the efficiency shown in CDBS is quite high--410
mV/m/kW @ 1 km, although it has been speculated that maybe the ground
system, which is almost 60 years old if it has never been replaced, is in
serious disrepair. A deteriorated ground system could explain an efficiency
significantly lower than the value shown in CDBS. The pattern is a modified
cardioid with radiation minima 31 or 32 degrees off axis at 219 degrees to
protect WWRL and at 282 degrees to protect E Longmeadow. (A true cardioid
consists of towers exactly 90 degrees apart and has only one radiation
minimum, along the axis of the array.)

WKOX, which, at night, currently also uses a two-tower array to produce a
modified cardioid pattern, has even taller towers. (They are top-loaded to
an electrical length of 214 degrees.) These produce even higher
efficiency--426 mV/m @ 1 km using a power of 1 kW. The axis of WKOX's array
is 35 degrees; in other words, WKOX's current pattern is rotated
counterclockwise from WUNR's pattern by 35 degrees. I believe that WKOX was
built that way because, when the move to 1200 was granted, secondary
stations on what had been Class IA channels were restricted to 1 kW at
night. The 35-degree orientation allowed a 1 kW signal to cover Marlborough
pretty well at night. Had WKOX been allowed higher night power when it first
moved to 1200, the orientation of its towers would probably have been more
clockwise because the azimuth of WOAI is 33 degrees clockwise with respect
to the azimuth of WKOX's towers. (And then later on when WBIX moved in with
WKOX, it would not have needed to use lower power during critical hours.)

When it looked as if Newton would never approve tower construction at 750
Sawmill Brook Parkway, I urged that WKOX move there anyhow and use WUNR's
two existing towers to operate DA-2. It turns out that the existing WUNR
towers have, within inches, the same physical spacing as the WKOX towers
(105 degrees at 1600 is 78.75 degrees at 1200). Running 50 kW-D from the
existing WUNR towers should have presented no problem for WKOX. The night
power would have had to be much lower than 50 kW, however. Because the WUNR
towers' more clockwise orientation would have reduced radiation to the
northwest, it might have been possible for WKOX to run 5 kW at night and
still adequately protect CFGO--I'm not sure. But even with 5 kW from a site
within the City of Newton, it did not appear that WKOX could deliver an NIF
signal to the requisite 80% of the CoL's population. Hence, the FCC would
have had to grant a waiver.

At 1200, WUNR's existing towers are 153.75 degrees high. The resulting
efficiency would have been about 7.5% higher than what WKOX will achieve
from its new 195' towers--the equivalent of more than 15% higher power--not
a huge difference, but not trivial either. Since there will be five towers
at the site (of which WKOX will use only three), and two of the three
stations that share the site are on frequencies lower than 1600, the area
covered by the new ground system will be greater than that covered by the
existing WUNR ground system. Part of the reason that WKOX is projecting an
efficiency as high as 339 mV/m/kW @ 1 km, is that the ground system of the
two towers that WKOX will not use is still considered to be part of WKOX's
ground system. If WKOX were going to use the existing WUNR towers, a larger
than normal ground system could also have been employed, somewhat improving
on the antenna efficiency that would have been achieved from the
153.75-degree towers.

Dan Strassberg, dan.strassberg@att.net
eFax 707-215-6367

----- Original Message -----
From: "Laurence Glavin" <lglavin@mail.com>
To: "Dan Strassberg" <dan.strassberg@att.net>; "Garrett Wollman"
<wollman@csail.mit.edu>; <bri@bostonradio.org>
Sent: Saturday, October 07, 2006 12:15 PM
Subject: Re: WITS/Red Sox

>----- Original Message -----
>From: "Dan Strassberg"
>To: "Laurence Glavin" , "Garrett Wollman" , bri@bostonradio.org
>Subject: Re: WITS/Red Sox
>Date: Fri, 6 Oct 2006 14:49:15 -0400 In any event, if you find WKOX's
current signal listenable for
>only a short distance past Worcester (I find it pretty good all the way to
>the Connecticut border on I-84), the new, "stronger" signal will become
>unsatisfactory to you near the west side of Framingham.

In this particulat case, I wasn't doing any radio-geekery, that is trying to
hold a station to see how far it would go;  I was actively listening to
Stephanie Miller and wanted to continue to do so.  I knew AM 1600 in
suburban Springfield was carrying it and when I flipped to 1600 I
expected a battle between it and WUNR, but was surprised to get the
station I wanted quite clearly.  In the past I never had any reason to
sample AM 1600 out of Longmeadow, so I had no idea what I'd find.
It does indicate that even during the day, WUNR's signal WNW is no great
which backs up your previous assertion that the Samill Brook location
isn't exceptional, even though those towers APPEAR efficient for a
1600 khz operation.

Play 100s of games for FREE! http://games.mail.com

More information about the Boston-Radio-Interest mailing list