Why do some stations have to change their antenna patterns or lower their power output during "critical hours" (a couple hours after sunrise, and a couple of hours before sunset). Why is it only some stations? WMEX in its 50 kw days used to do this (switching to a different pattern) and WXEX in Exeter NH does this (dropping from 5 kW to 2.5 kW). Is it frequency dependent (both WMEX and WXEX are above 1500 kHz). Is it a case by case thing based on other stations on the same or adjacent frequencies? I've always wondered why it is some stations, not all.
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Critical Hours
- Thread starter AerieAlso
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So WMEX did it to protect WLAC, and WXEX does it to protect ZNS-1 (or possibly still WPTR/WDCD).
But WRKO, WEEI, and WXKS co-channel Class A stations (KNBR, KOA, WOAI) are far enough to the west/south that they would not be affected until sunset in Boston (when WRKO, WHDH, and WXKS go to night patterns anyway)?
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WPTR/WDCD was a class B station that didn't have skywave protection.
The WEEI and WRKO facilities predate 1959, when the critical hours rule was implemented. I'd have to go back and look at the WXKS applications to see why there's no need for CH protection to WOAI.
The WEEI and WRKO facilities predate 1959, when the critical hours rule was implemented. I'd have to go back and look at the WXKS applications to see why there's no need for CH protection to WOAI.
AerieAlso, welcome to the group. You are interested in nuances of AM station technical operation, indeed.
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WILD-1090 also has lower power during "Critical Hours".
Although their transmitter site will be moving from Medford to Quincy, the reduced "Critical Hours" power will still be the case (Current: 4,800 watts day/1,900 watts "Critical Hours"; CP: 2,700 watts day/1,800 watts "Critical Hours).
WILD once had 1,000 watts; it's power was boosted to the current level in the late 1970's but had to adopt lower power during "Critical Hours" when it boosted daytime power. Even still, it's "Critical Hours" power is higher than it's old daytime power.
The new site will actually mean a better signal in coastal communities, especially along the North Shore.
Although their transmitter site will be moving from Medford to Quincy, the reduced "Critical Hours" power will still be the case (Current: 4,800 watts day/1,900 watts "Critical Hours"; CP: 2,700 watts day/1,800 watts "Critical Hours).
WILD once had 1,000 watts; it's power was boosted to the current level in the late 1970's but had to adopt lower power during "Critical Hours" when it boosted daytime power. Even still, it's "Critical Hours" power is higher than it's old daytime power.
The new site will actually mean a better signal in coastal communities, especially along the North Shore.
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