WWZN and Kinstar antennas

[Dan Strassberg]

The company behind KinStar is northern-Virginia based Kintronics, which I
believe is the largest manufacturer of phasors for AM DAs. The WWZN array is
four towers--two used by day (same pair for both D and CH); all four used at
night. Remember, the WWZN towers are 198 degrees and hence are quite
efficient (better than 400 mV/m/kW @ 1 km). Given the high-on-the-dial
frequency and the abysmal soil conductivity near the site, that efficiency
was necessary to get 25 mV/m over the CoL's "principal business district."
That signal level, though no longer required, was required in 1981 when the
array was constructed.

The KinStar design is heavily top loaded and, in its way, very reminiscent
of a lot of MW transmitting antennas built in the '20s and early '30s. Many
of them started out as horizontal longwires. More than a few of those were
converted to vertical radiators with the longwire portion becoming, in most
cases, a "bedspring" top load for the vertical element, which had started
life as the feed line to the horizontal radiator. A lot of these antennas
had decent efficiency but few achieved the Class B miinimum of 281.7 mV/m/kW
@ 1 km or the typical efficiency of a 90-degree series-fed radiator with 120
quarter-wave ground radials (approximately 306 mV/m/kW @ 1 km). Kintronics
is not claiming the ability to achieve much more than quarter-wave
efficiency from the KinStar design. As I see it, Louis duTreil's big
contribution to the KinStar technology (besides his copious measurements) is
his design of several matching network topologies that allow standard MW
transmitters to drive the extremely low impedance of the short antennas.

I would not put any money on the likelihood of getting local approval for
constructing a KinStar DA in the Waltham-Belmont area, even though it might
be accomplished by using 50' wooden telephone poles. This is NIMBY country
and the folks around Waverly Sq who haven't been able to use their
telephones without hearing WWZN (or all of the many call signs the station
has had over the last quarter century) are not likely to soon forget the
problems they have been living with. It will take an organization as well
financed, as determined, and as patient as CCU was about the Oak Hill
WKOX/WRCA/WUNR site to make any changes in the WWZN array that require
modification or construction of towers. Now, a diplex from the WMKI site
might be a different story but the night power would have to be throttled
back big time--to the point where a CoL change would probably be required,
and THAT will have to wait for a new AM filing window, which is not even a
prospect until 2008 at the earliest.

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

----- Original Message -----
From: "Aaron Read" <readaaron@friedbagels.com>
To: <boston-radio-interest@bostonradio.org>
Sent: Tuesday, May 09, 2006 10:26 AM
Subject: WWZN and Kinstar antennas


>
http://lists.bostonradio.org/pipermail/boston-radio-interest/2006-May/008583
.html
>
> Part of WWZN 1510's big problem is the outrageously high rent they're
> paying for their land lease.  IIRC it's something in the tens of
> thousands per month?
>
> Of course, finding a new place to put a five tower array (it is five
> towers, right?) is not a trivial thing.  Not with such a highly
> directional pattern.
>
> However, since WWZN has such a high frequency, I think they may be able
> to get out of their current location within a few years using the new
> Kinstar antennas.  Kinstar is not yet FCC-approved for anything but omni
> AM's but that will almost certainly change once Kinstar finishes the
> research on it.  --
>
> --------------------------
> Aaron Read
> readaaron@friedbagels.com
> www.friedbagels.com
> Boston, MA 02176
>
>
>