750 CP's

Dan.Strassberg dan.strassberg@att.net
Fri Jun 5 06:24:44 EDT 2009

That was true of the old US IA's (except for WJZ/WABC, which was a
special case because of KOB's uncertain status). But it was not true
of Mexicans or Canadians. Full-time stations were allowed in Canada on
Mexican IA channels but full-time US stations weren't. Canada's
situation was even more complex. On Canadian IA channels, full-time US
stations were allowed if they were sited at least 650 miles from the
nearest point of land in Canada. On 740, this rule allowed some
powerful US full-timers including KCBS, KTRH, KRMG, and a 50-kW in
Florida (Orlando area, I believe), whose calls I can't remember.

However, the prohibition against full-time US stations (besides KOB)
on US IA channels was gradually eroded. When 540 became a
Mexican/Canadian IA channel, KFMB, which was in the throes of moving
from 550 to 540, was suddenly displaced. The FCC moved it to 760 with
5 kW-U DA-N. Then (in the 60s, I believe) the FCC opened up
approximately half of the IA channels to Class IIA stations, a new AM
class that was intended to provide nighttime skywave service to
underserved areas, mostly west of the Mississippi. Those stations'
skywave coverage was, admittedly, compromised by the skywaves of the
co-channel IAs. The status of the remaining 13 or so IA channels was
held in abayance while the FCC and the industry continued the
seemingly endless debate over superpower, which would have allowed
half of the IAs to operate at 750 kW-U. WBZ wanted to construct a new
transmitter site in Provincetown with 500 kW DA-1.

And broadcasting legend George Storer then entered the picture. He
owned KGBS in Los Angeles (now KTNQ) on 1020, which had to sign off at
local sunset to protect KDKA. A Class IIA was assigned to 1020 in New
Mexico and he struck a deal with the owners of that station (and the
FCC approved) to pay for the NM station's upgrade to 50 kW-U provided
that the NM station protected the new 50-kW nighttime service of KGBS.
His claim was that the coverage area of the NM station (KSWS, I think)
completely "shadowed" the coverage area he proposed for KGBS, which
thus would not cause any additional interference to KDKA. That deal
became a precedent for other limited-time West Coast stations on US IA
channels to become full timers with substantial night power. KGBS was
soon joined by KFAX (50 kW-N) and KXL (20 kW-N).

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

----- Original Message ----- 
From: "Dave Doherty" <dave@skywaves.net>
To: "Dan.Strassberg" <dan.strassberg@att.net>; "Sid Schweiger"
<sid@wrko.com>; <bri@bostonradio.org>
Sent: Thursday, June 04, 2009 9:57 PM
Subject: Re: 750 CP's

> Hi Dan-
> The old Class 1-A clears were originally protected by virtue of
> having no other stations operating at night on their frequencies. I
> believe that was the NARBA language, but it was definitely in the
> FCC rules way back when. Once we abrogated NARBA, the standard
> treaty obligations protecting service only on home soil came into
> play.
> And yes, the FM rules are the same. I do a lot of work in the border
> areas, sometimes with near-miraculous results.
> -Dave Doherty
> Skywaves Consulting LLC
> PO Box 4
> Millbury, MA 01527
> 401-354-2400
> 202-370-6357 (DC)
> ----- Original Message ----- 
> From: "Dan.Strassberg" <dan.strassberg@att.net>
> To: "Sid Schweiger" <sid@wrko.com>; <bri@bostonradio.org>
> Sent: Thursday, June 04, 2009 8:58 PM
> Subject: Re: 750 CP's
>> WJIB is a US Class D AM on a Canadian Class A channel. There are
>> many
>> such stations, but as a group, they constitute a special class as a
>> result of stations of all classes in North America (I think this
>> applies to FMs as well as AMs) now receiving protection within
>> their
>> normally protected contours only over land that lies within their
>> national borders. The reason these US Class Ds can now operate at
>> night, albeit in most cases with very low power, whereas they
>> previously had to sign off at local sunset, is that Class A AMs
>> used
>> to receive protection within their 0.5 mV/m 50% skywave contours
>> even
>> when those contours extended into areas outside the Class As'
>> national
>> borders.
>> The Toronto Class A (CFZM? ex-CBL) delivers a 0.5 mV/m 50% skywave
>> signal hundreds of miles to the southwest of Boston. That's the
>> contour that would receive protection of it were in Canada. As it
>> is,
>> the contour covers many thousands of square miles of US land where
>> it
>> no longer has to receive protection. However, WJIB must protect the
>> point of land where this contour intersects the Canada/US border.
>> Thus, WJIB could, indeed, increase its night power quite
>> substantially
>> if Bob wanted to spend millions of dollars to install a
>> sufficiently
>> complex directional antenna--assuming he could find land on which
>> to
>> construct it.
>> In theory, WJIB could run perhaps 50W at night (give or take) if
>> Bob
>> wanted to pay rent to American Tower systems to use its towers at
>> the
>> WWDJ/WAZN site in Lexington. A two-tower array for 740 that
>> protected
>> the Canada/US border could be constructed using the tall (FM) tower
>> and one of the AM towers. That array could limit the signal toward
>> Canada to the equivalent of 5W ND over a substantial arc while
>> delivering the equivalent of perhaps 80W ND over Belmont and parts
>> of
>> Watertown and Cambridge. Since WJIB would still be restricted to
>> using
>> much less than 250W at night, it would remain a Class D, meaning
>> that
>> it would not have to deliver an NIF signal to any of its CoL,
>> Cambridge--and it probably wouldn't do so. But the densly populated
>> area within a mile or so of the WJIB tower that currently receives
>> pretty good signal at night would no longer do so because the
>> transmitter would have moved further away.
>> And it would be an expensive project. The FM tower would have to be
>> skirted; it is a grounded-base tower, so a so-called Folded Unipole
>> AM
>> antenna would have to be installed on it and a ground system would
>> have to be installed around the tower base. The expense and the
>> problems don't stop there, though. Two stations, WWDJ and WAZN,
>> already use the site, so the filtering problems would be quite
>> complex. And the site is only a couple of miles from 50-kW WWZN.
>> Filtering that enormous signal would be a huge headache. And
>> remember,
>> the second harmonic of 740 is 1480, only 10 kHz from WAZN. I hope
>> that anyone who thinks this project might be practical knows how to
>> pronounce engineering nightmare.
>> -----
>> Dan Strassberg (dan.strassberg@att.net)
>> eFax 1-707-215-6367
>> ----- Original Message ----- 
>> From: "Sid Schweiger" <sid@wrko.com>
>> To: <bri@bostonradio.org>
>> Sent: Thursday, June 04, 2009 2:34 PM
>> Subject: RE: 750 CP's
>>>>it sounds like this applies to every station
>> indiscriminately.  Apparently WJIB, with its 5-watt nighttime
>> signal,
>> can't make any transmitter upgrades without degrading its night
>> signal.  Nor can WBZ, with its 50,000 watts clear-channel.  Does
>> this
>> really make sense?<<
>> WJIB would certainly be able to show the Friendly Cookie Company
>> that
>> ratcheting back its nighttime signal would have close to zero
>> effect
>> on any other co- or adjacent-channel signal.  I can't say if a
>> waiver
>> of the ratcheting policy has ever been granted, but that doesn't
>> mean
>> they couldn't try.  Waivers are granted at the FCC for all kinds of
>> reasons.
>> Sid Schweiger
>> IT Manager, Entercom New England
>> 20 Guest St / 3d Floor
>> Brighton MA  02135-2040

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