Re: WJIB Night-time power

[Dan Strassberg <dan.strassberg@worldnet.att.net>]

At 11:29 AM 9/7/98 -0400, you wrote:

>        I also wonder, Why didn't the CBC ever go to DAs or otherwise fix
>their signal problems? How about moving the transmitter site? A related
>question is why Canada set the 50 kW limit on its I-A/now A stations at
>all. It has a vast territory and there was no particular reason for the 50
>kW limit in terms of international dealings, as those channels were, almost
>without exception, for Canada to use as it saw fit. If 740 and 860 were 150
>kW, I'll bet they wouldn't have their downtown Toronto problems. And, as
>far as I understand the treaties, they could go to 150 kW tomorrow and all
>the U.S. stations that use those channels at night would just have to take
>whatever interference they received.
>
The Canadian "clear channels" have for many years been home to a number of
high-pwered true-full-time AMs in the US. For example, 740 has KCBS in San
Francisco, KRMG in Tulsa, KTRH in Houston, and a 50 kW-U in Orlando. US
full-timers located more than 650 miles from the nearest point of land in
Canada have been permitted on these channels for well over 50 years.
Canadian clears cannot increase radiation at night in the direction of these
stations. Also, Canada itself has used these channels for secondary
stations. On 740, for wxample, you find a 50 kW-U station in Edmondton and a
10 kW-U somewhere in the Maritimes or Newfoundland (CBNM Marystown, I believe).

The situation with respect to WJIB, WGSM, and the other daytimers with night
authorizations on Canadian Class A channels is different, however. These
stations receive no protection from nighttime interference. A different
operation in Toronto that increased radiation in their direction would be
permissible.

An interesting but little-known fact about CBM is that it is technically
DA-2. The day and night patterns are identical, as far as I can tell, but
the antenna parameters, though actually identical day and night, are
described differently in the database. CBM really does use two towers (the
second one is presumably CBF's auxilliary). The pattern slightly limits
radiation to the south. I assume this is done to protect the US full-timers
on 940 as well as the co-channel Mexican Class A.

On 990, CBW is ND-U but uses 46 kW at night vs 50 kW-D. My guess about this
is that, at some point, the station installed a more efficient antenna and
had to slightly reduce its nighttime power to restrict radiation toward the
US and Mexico to its former values.

- -------------------------------
Dan Strassberg (Note: Address is CASE SENSITIVE!)
ALL _LOWER_ CASE!!!--> dan.strassberg@worldnet.att.net
(617) 558-4205; Fax (617) 928-4205

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