Posted by
jammerdave on Wednesday, November 07, 2007 5:44:46 PM
I'll start this off by telling ya'll about an email that I received, which is really a fairly frequent question from our AM station listeners:
"At around 5 pm every night I cannot get station any more for the last 3 days. Is there and issue with signals?? I live in Placerville and it has worked fine for years."
My response was:
First off, thanks for listening to our station! We appreciate that.
The reason that your reception changes at 5PM each day, is due to our compliance with FCC regulations that cause us to lower our power level and change our antenna radiation pattern at the average sunset (as well as sunrise). That time for November during PST is 5PM. We resume our normal power and pattern at 6:45AM each morning. This will change again in December and so on. We apologize for the inconvenience, but there is nothing we can do about it. The reason that it is done is to protect distant stations from interference, as AM radio waves carry much further during the evenings.
If you have access to a computer during the times that you wish to listen, please try our streaming audio Which can be accessed via our web site, http://www.kfia.com look for the "click here to listen" link on the left side of the web page.
Thanks,
Dave Fortenberry
Chief Engineer KFIA/KTKZ/KKFS radio
Let me add that many AM stations are required by FCC mandate to reduce power and/or change their antenna patterns at sunrise and sunset. This is to protect other stations on the same and adjacent frequencies. As many folks know, AM signals carry *much* further at night due to what is called "skywave" propagation, and is especially prevalent during the winter months. When conditions are right, signals can and do travel around the world. I will get an occasional request to verify reception of KTKZ from Finland or some other distant country. Pretty cool, eh? Skywave propagation is what pulled me in to this business to begin with. When I was about 10 or 11 years old, I was listening to an old tube clock radio that I had bought at a garage sale. When I should have been asleep, I was instead dialing around on the radio and discovered KTWO in Casper, Wyoming! (I was in Napa, CA back then) I thought, "how is this possible?". It just sort of snowballed from there, and here I am today.
Generally speaking, the newer the station is, the more restrictive the standards to which they must adhere to. AM station directional antenna systems are there to *pull in* signals in certain directions (to protect others), not to beam more signal to certain places. Does this make sense? I hope so. As an engineer, the dream station would be a 50,000 watt non-directional signal with no restrictions as to day & night operation. Those do exist, and they are great, but many more are far more complicated than that.
C'mon, somebody throw something else at me...