Re: [IRCA] KSLM 1390 // KFXX 1080 "The Fan"

[Scott Fybush <scott@xxxxxxxxxx>]

Patrick Martin wrote:
> Scott,
> 
> One question. Now if they do have a taller tower, dropping to 690 watts
> from 1 KW, would I get exactly the same signal (S meter reading) than I
> got before. In otherwords, would the 690 watts get out as good as the 1
> KW? 

That's more or less the idea. Within the limitations imposed by a given 
station's class (no more than 1 kW for a class C "graveyarder," no more 
than 50 kW for class A, B and D stations), the FCC's not concerned as 
much with how much power goes INTO the antenna as with how much field 
strength comes out of it.

In the case of a station like KSLM, it's pretty well locked into its 
existing contours by everything else on and near 1390, so changing 
transmitter sites or towers won't buy it any more reach. What the FCC 
looks at in a move like that is where the signal contours fall, which is 
a function of both raw power into the antenna and the antenna 
efficiency. The 690-watt level was no doubt chosen to produce the same 
field strengths that 1000 watts did from the old tower, which means the 
signal you receive should be about the same.

Back in the days before "dial-a-power," when the FCC only allowed 
stations to operate at certain fixed power levels (1, 5, 10 kW, etc.), 
it was not uncommon for stations to deliberately reduce the efficiency 
of their antenna systems to be able to use the next power level up. So a 
station that might not quite fit in at 5 kW, but which wanted more reach 
than 1 kw would give, might apply for 5 kW with an antenna system that 
included a big resistor to dissipate some of the power along the way. 
Today, that station would simply be licensed at 3200 watts, or whatever.

s
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