Directional ex-Class IA AMs

Scott Fybush
Mon Nov 23 12:28:08 EST 2009

Dan.Strassberg wrote:

> It was not very directional
> and the radiation efficiency was HUGE--much higher than that of WTAM's
> current conventional half-wave tower. I don't know the height of the
> old tower; presumably, it was more than helf wave--maybe as much as
> 5/8 wave.

The old tower still stands - it was also the tower for WTAM's sister TV 
station, WNBK, which is today's WKYC-TV 3. The tower is 278 meters 
(911') tall. I don't recall whether it was segmented or not. I suspect 
it must have been - 278 meters is almost exactly a full wavelength at 
1100 kHz, so segmenting it with an insulator halfway up would create a 
near-perfect Franklin antenna.

That site is indeed south of Cleveland, in the Parma/Seven Hills antenna 
farm near the junction of I-480 and I-77. The previous WTAM site, to 
which WTAM returned after its experiment with DA operation, is a few 
miles to the southeast of the TV tower in Brecksville. (It's still the 
current WTAM site.)

> There were other Class IA AMs that might have benefitted from using
> DAs but never chose to do so. The most notable was KFI, which, back in
> the '30s, could have built a two-tower array (or even a one-tower
> setup like WTAM's) on Catalina Island. I suspect, however, that KFI's
> owner, auto dealer Earl C Anthony, figured that the publicity from
> having the station's 750' tower right next to his auto dealership was
> a good trade-off for the coverage KFI could have gained in southern
> California's then-sparsely populated desert areas. Also, there might
> have been problems with getting the audio to a transmitter "26 miles
> across the sea." I don't know in what year Pacific T&T installed its
> first undersea cable between Santa Monica and Avalon.

The Army beat the telephone company to that particular task - there was 
a cable in place by 1923, though it had only 7 circuits available at first.

But the challenges of operating a 50 kW transmitter from Catalina back 
then would have been stiff ones. A fulltime engineering staff would have 
to have been housed on the island, and KFI would likely have needed to 
operate its own generator as well.

I should correct a misconception here, while I'm at it: when Earle 
Anthony built the current KFI transmitter site in 1931, it was not next 
to his auto dealership. The dealership was in downtown LA, crowned by 
two big towers that continued to advertise KFI long after the 
transmitter moved out of the city. The transmitter site in La Mirada, on 
the Orange/LA county line, was surrounded by orange groves as late as 
the 1980s, when then-owner Cox built warehouses over the ground system 
around the tower base.

> As for what stations the directional operations protect, although that
> was not an issue when any of these ex-IA stations was built, changes
> in the FCC rules might make it an issue now if WBZ or WWL wanted to
> abandon its DA-1 operation. WBZ's radiation toward a station in Puerto
> Rico might become an issue if WBZ wanted to operate ND. And I believe
> that there is now at least one full-time station on 1030 in Florida.
> WWL's limited radiation to the south now protects several signals in
> (I believe) Venezuela and surrounding countries.

That's an interesting question. Before the latest incarnation of the Rio 
treaty, it's my understanding that as I-A stations, WBZ and WWL operated 
directionally at their own discretion and could revert to ND operation 
at will. A former WBZ engineer once told me a story of a visit from a 
newly-minted FCC field agent, who showed up to inspect the site and 
wanted to go out and examine the station's monitoring points to 
determine whether the DA was operating properly. Trouble was, there were 
no monitoring points specified on the license, since WBZ was essentially 
a de jure ND station operating as a de facto DA.

That was all well and good when WBZ had 1030 to itself. It would not 
work as well now, with stations jammed on to the channel right up to the 
edges of WBZ's protections.

My guess is that the DA operations at WBZ and WWL are effectively 
grandfathered in place now that the I-A/I-B distinction has been 
eliminated, and any changes either station might make in the future 
would be handled under the same rules that apply to any class A AM signal.


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