Daytime AM Sign Off Time

[shreveville]

I know of a 5 KW Daytime AM that always signed off at 9 PM Eastern in June. I assume it is the same, but when I check the sunset times on the FCC website it lists sunset as 10:30 PM instead of 9 PM. Am I doing something wrong?

 

[TomZ]

Could Daylight Savings Time be part of this observation?

 

[semoochie]

June is 9PM here. It almost works by zipcode. A little bit east or even south can change the results but 10:30 seems way off the scale unless you're in the Arctic Circle or something.

 

[shreveville]

I agree Semoochie, it has always been 9 PM here. Is there a list of AM station sign off times on the Internet? Would love to see it in writing. Love to see it say 9 PM. ;D

 

[grich]

This is the current location for the FCC's sunrise/sunset calculator...I'm guessing the link will change soon:
http://transition.fcc.gov/mb/audio/bickel/srsstime.html

 

[shreveville]

There is a link on that site labeled "Find Community Coordinates program." Unfortunately that link on the FCC website is dead. Without that, I don’t know what latitude and longitude to enter. Is there another source to find this information?

 

[semoochie]

Go back to the same page and click on "AM Query". If you put in a set of call letters, it will show the coordinates for that station.

 

[shreveville]

Thanks Semoochie. I now have the correct times thanks to you.

 

[Bengalsfan]

You need to determine who's daytime the station is signing off to. For example, WCKY in Cincinnati is a 50kW station with different day/night patterns. HOWEVER, they do not switch to night time pattern until it's sunset at KFBK in Sacramento, CA. This station may not need to sign off until it sunset at the station they are protecting.

 

[semoochie]

You're welcome! "You need to determine who's daytime the station is signing off to. For example, WCKY in Cincinnati is a 50kW station with different day/night patterns. HOWEVER, they do not switch to night time pattern until it's sunset at KFBK in Sacramento, CA. This station may not need to sign off until it sunset at the station they are protecting." If that's the case, it isn't a daytimer. It's a "limited time" station, designed to only protect the Class A station on the frequency. One such example is what was, for the last 85 years, KXL(now KXTG)Portland, protecting WSB Atlanta. I'm a little confused by your statement though because I thought it was the other way around, with KFBK protecting WCKY but I was always unsure about the band above 1500 anyway.

 

[Bengalsfan]

Could Daylight Savings Time be part of this observation?

Depends if the license is printed in DST. Most licenses are printed in standard time. If you have a clock or timer controlling your night time power/pattern, you program it to what the license reflects then set it's time to standard time and leave it there. No need to adjust for savings time. I have a license printed (in eastern Kentucky) on Central time. The Sine is programmed to turn the transmitter off at the times according to the license and the clock on the Burk is set to Central Standard Time, and left there.

 

[DanStrassberg]

I'm a little confused by your statement though because I thought it was the other way around, with KFBK protecting WCKY but I was always unsure about the band above 1500 anyway.

The ex-IB channels on which some stations operate with their daytime facilities after local sunset used to be 1080, 1530, and 1560. The more eastern IB on each channel (WTIC, WCKY, WQEW) could stay on day pattern and power until local sunset at the co-channel 1B (KRLD, KFBK. KNZR). 1080 was recently deleted from this group, however. On 1110, the situation was (and I think still is) the reverse. KFAB can switch to day pattern (ND) at sunrise in Charlotte NC. On 1530 and 1560, at least some of the Class B stations located west of the eastern iB and east of the western 1B use different operating parameters (pattern and power) for the period between sunset at the eastern 1B and local sunset at the Class B. (For example, look at the 1560 in Paducah KY.) Except for 1110, some of this suggests that the eastern 1B is dominant on the channel and some of it suggests that the western 1B is dominant. In fact, there may have been no choice of which 1B was (is) dominant--one of the 1Bs was allowed to use its day facilities as long as only one of the 1Bs was in darkness. Co-channel Class Bs always protected the co-channel 1B to their east.

1080 was removed from this list when a station in MI (currently a daytimer) that holds a CP for 50 kW-D/2.<something> kW-N DA-2 using a six-tower array day and night and is located within what was WTIC's protected 0.5 mV/m 50% nighttime skywave contour when WTIC was operating ND after Hartford sunset, protested that observing the rule was going to force it to sign off at its own local sunset and not sign on again until Dallas sunset. The FCC eventually ruled that WTIC's license guaranteed no protection to its skywave service during post-sunset hours when it operated with its daytime (ND) facilities. At that point, CBS (which happens to own both of the 1Bs on 1080) decided not to fight and to change WTIC's operation to DA-N between Hartford sunset and Hartford sunrise. I believe that automatically modified the licenses of all Class Bs on 1080 that used special parameters during the period between their local sunset and Dallas sunset. Man...until I tried to write this down, I didn't realize how complicated it was(!)

Something else that puzzles me is the 1110 situation. Until sometime in (I believe) the 60s, if the the easternmost 1B on any 1B channel used different pattern and/or power at night, it was allowed to change to its day facilities at 4:00AM local standard time. The old WNEW (AM 1130) in New York City switched to its day facilities at 4:00AM when standard time was in effect and 5:00AM during Daylight Saving time. Now, this was an even better deal than KFAB had--being able to go ND at Charlotte sunrise. So it appears that the special provisions in KFAB's license did not take effect until the FCC started requiring 1Bs to stay on night pattern until local sunrise. So that means that KFAB's special situation is not grandfathered from the date of NARBA (March 1941) but rather, from several decades later.