Boston-Radio-Interest Digest, Vol 9, Issue 37
Thu Feb 3 13:26:25 EST 2005
I think you are talking about a scheme for creating a "single-tower" AM DA.
The scheme was used only once to my knowledge. It was the brainchild of the
late engineer Carl Smith of Cleveland OH, who, in his day, was considered by
many to have been the premiere designer of AM DAs. Smith's name still graces
a consulting-engineering firm that is widely regarded as one of the two or
three premiere designers of AM DAs. I believe that the Carl Smith Company
was the outfit that finally figured out how to adjust WBIX's very demanding
five-tower array. By some technical sleight of hand that I don't understand,
one of The Smith Co's engineers figured out how to rotate a spurious lobe
from about 240 degrees, where it pointed right at KYW, to about 350 degrees,
where it interferes with nothing.
Anyhow, the "one-tower" DA was used successfully for many years by WTAM
in Cleveland. Although there was only one tower, the array consisted of two
elements. One was the tower, AFAIK, a conventional series-fed structure. The
other element was a vertical wire dropped from one of the guy wires and
insulated from the guy. Of necessity, the spacing between this element and
the tower was pretty short and the tower heights were unequal. Apparently,
the WTAM site was located close to the Lake Erie shore. That is, it was
mainly either east of west of Cleveland. The pattern was designed to reduce
radiation to the north--over the Lake and southern Ontario. The signal in
that direction was not negligible, however. The signal to the east, west,
and south was stronger, however.
The arrangement sounds practical, so I am surprised that no other station
has tried it. There are several stations that have used (and a couple that
still use) vertical wires suspended from horizontal wires as DA elements. Of
these, the best-known was WOR, when it operated from Carteret NJ. Another is
KSUR 1260 in--I think--Beverly Hills CA. A third is the 1510 station
currently licensed to a community near Oakland CA. If I'm not mistaken, the
1260 and 1510 stations are both owned by Saul Levine. The 1510 station is
also unique in having the only rooftop DA in the US. I suspect that the WOR
Carteret array began life as a long-wire but was later converted to a DA.
The first DA, at shartetimers WFLA/WSUN in Tampa-St Petersburg, went on the
air in 1931. By 1936, WOR's antenna was being operated as a DA.
Dan Strassberg, email@example.com
----- Original Message -----
From: "Keating Willcox" <firstname.lastname@example.org>
Sent: Wednesday, February 02, 2005 2:38 PM
Subject: Re: Boston-Radio-Interest Digest, Vol 9, Issue 37
> At 12:00 PM 2/2/2005, you wrote:
> >It seems to me that a few months ago I came up with 300W ND-D from the
> >site, which is several miles north of what had been WSMN's site. I'd
> >have to check that figure, though. 300W might be adequate to cover Nashua
> >and Merrimac by day, but I imagine that, at night,
> WMVU Nashua at900w daily had a super tower - wet feet - it would go
> forever. I read somewhere that by putting some juice on the guy wires, you
> could add some direction to the signal. Anyone have any other weird ideas?
> Keating Willcox ~/~
> WNSH AM 1570 Beverly
> 'playing the best music ever recorded'
> 978-921-1570 FAX 978-468-1954
> 376 Hale Street, Beverly, MA 01915
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