The future of AM radio

[Dan.Strassberg]

Although it's possible, I rather doubt that the Herald Traveler had
any thoughts of upgrading WHDH to a Class IB. I suspect, instead, that
the tall towers were nothing more nor less than a way to maximize the
groundwave coverage in a region whose poor soil conductivity is
legendary. Although CDBS lists the electrical length of all three
towers as 207 degrees (because of "mutual inductance;" 207 degrees is
greater than 5/9 wavelength but less than 5/8), the towers are of
unequal heights, part of a largely unsuccessful strategy to minimize
selective fading in areas where both the groundwave and skywave are
received. The west tower is 640' (199 degrees); the center tower is
600' (186.7 degrees--including the section at the top that is
removable--but was never removed--for mounting of a top-mounted FM
antenna); and the east tower is 560' (174.3 degrees).

Both WHDH and WLAW upgraded to 50 kW shortly after World War II. Most
likely, the planning for both upgrades was done before the war. I'm
sure there was intense competition between the consulting engineers to
design the better facility (that is, the one that provided superior
coverage). It was no secret that, because of its lower frequency, WLAW
had a natural advantage in coverage. Curiously, the fact that WLAW was
licensed to Lawrence but wanted to serve Boston forced on it a
transmitter location and a directional pattern that were, for the most
part, superior to WHDH's. WHDH's tall towers were almost certainly
part of an effort by its engineers to level the playing field as much
as possible. I don't know whether Hanscom Field existed when WLAW was
planned and built, but if the airfield existed or was itself in the
planning stages, both sets of engineers realized that WLAW could never
have towers anywhere near 1/2 wavelength.

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

----- Original Message ----- 
From: "Martin Waters" <martinjwaters@yahoo.com>
To: <boston-radio-interest@bostonradio.org>; <wollman@bimajority.org>
Sent: Saturday, February 02, 2008 1:09 PM
Subject: Re: The future of AM radio


>
> --- Garrett Wollman <wollman@bimajority.org> wrote:
>
>    The WEEI towers are very tall -- around 5/8th
> wave, IIRC. As a result, I've always wondered whether
> WHDH/Boston Herald-Traveler had a plan to try to get
> the station designated as a I-B and built the antenna
> to those specs.
>