What is the Critical Hours for am?

[jras20]

What is the Critical time hours in the night for AM? I never realy knew that.
Thanks in advance!
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jras20</P>

 

[gr8oldies]

6am-local sunrise

 

[techie]

> What is the Critical time hours in the night for AM? I
> never realy knew that.
> Thanks in advance!
>

From the FCC AM database:

Critical Hours is that time from Sunrise to
two hours after Sunrise, and from two hours
before Sunset until Sunset, local time.
During that time, certain stations may be
operating with reduced facilities as a result
of Section 73.187 of the Commission's Rules.

 

[gr8oldies]

I messed up..I was thinking the pre-sunrise power times.

 

[Tom_]

Why does the following scenario not seem occur that frequently:

1. A class B station currently operates with 5,000 watts non directional day, 1,000 nd at night.

2. The 5,000 watts directional day COULD be 50,000 watts DIRectional or even nd and still NOT interfere with other station(s).

But that can't occur due to skywave during critical hours that WOULD interfere w/ other station(s).

3. Why doesn't the station apply for 50,000 watts nd or DIRectional, but remain at 5,000 watts non directional during critical hours, and remain at 1,000 nd at night.

Here's an interesting scenario: AM 810 KTBI Ephrata, Wa. Class D is 50kW day nd, 23kW nd critical, off at night to protect KGO:

http://www.radio-locator.com/cgi-bin/info?call=KTBI&service=AM