AM primary station to Translator separation

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Ray
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AM primary station to Translator separation

Post by Ray »

Does part 74.1201 (g) apply for a AM (class B) primary station to lease a FM translator that is well beyond the primary station's 1mV/meter coverage area? The translator location is actually close to the 0.1 mV/meter primary contour.

(g) Translator coverage contour. For a fill-in FM translator rebroadcasting an FM radio broadcast station as its primary station, the FM translator's coverage contour must be contained within the primary station's coverage contour. For purposes of this rule section, the coverage contour of the FM translator has the same field strength value as the protected contour of the primary FM station (i.e., for a commercial Class B FM station it is the predicted 0.5 mV/m field strength contour, for a commercial Class B1 FM station it is the predicted 0.7 mV/m field strength contour, and for all other classes of FM stations it is the predicted 1 mV/m field strength contour). The coverage contour of an FM translator rebroadcasting an AM radio broadcast station as its primary station must be contained within the lesser of the 2 mV/m daytime contour of the AM station and a 25-mile (40 km) radius centered at the AM transmitter site. The protected contour for an FM translator station is its predicted 1 mV/m contour.
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Re: AM primary station to Translator separation

Post by TPT »

It's the greater of 25 miles from the tower or 2mv/m contour. Always check at ECFR.GOV for the current rule:

"The coverage contour of an FM translator rebroadcasting an AM radio broadcast station as its primary station must be contained within the greater of either the 2 mV/m daytime contour of the AM station or a 25-mile (40 km) radius centered at the AM transmitter site. "

Look at W300AQ's contour, which is a tenant on my tower. The translator rebroadcasts a Class C (1450) AM, the translator's tower site is well outside the 2 mv/m as well as the .5 mv/m---but still within the 25 mile circle from the tower, though some 17.5 miles from the transmitter site.

In this example, the translator needed to be directional to keep the 60 mv/m contour inside the 25 mile circle.

Now, FM stations can be carried on non-fill in translators, but the primary station can't own or support (with limited exceptions) that translator. Also, the rules limit power/coverage compared with a fill-in translator. I am not sure if an AM station can be carried on a non-fill-in translator.
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Deep Thought
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Re: AM primary station to Translator separation

Post by Deep Thought »

An AM fill-in translator cannot have a 60 dBu contour which exceeds the greater of the daytime 2 mV/m contour or a 25 mile radius circle from the AM transmitter site. There are no exceptions.

Another FM translator outside that area *can* rebroadcast the fill-in via direct off the air pickup of the fill-in translator but the AM licensee cannot have anything to do with it other than granting retransmission consent. A lease deal would run afoul of that rule. It also has to abide by the power vs height rules since it is not a fill-in.
Mark Mueller • Mueller Broadcast Design • La Grange, IL • http://www.muellerbroadcastdesign.com
knoxbob
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Re: AM primary station to Translator separation

Post by knoxbob »

here's one for you. WALI licensed to Dayton Tennessee has a translator licensed to Cleveland, Tennessee and it looks like their primary signals aren't anywhere close together. How could this one get approved.
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Re: AM primary station to Translator separation

Post by w9wi »

knoxbob wrote: Sun Sep 05, 2021 11:27 pm here's one for you. WALI licensed to Dayton Tennessee has a translator licensed to Cleveland, Tennessee and it looks like their primary signals aren't anywhere close together. How could this one get approved.
Best I can tell it's legal.

FCC database says W245DZ-96.9 relays WALI-1280. The attached JPG shows WALI's 2mV/m contour in green, and W245DZ's 60dBu in cyan. The contours don't even intersect. However, the 25-mile radius around WALI's tower is shown in blue -- W245DZ's 60dBu is indeed contained within this radius.
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WALI-and-translator.jpg
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Re: AM primary station to Translator separation

Post by knoxbob »

Thank you for the education. To me that kind of defeats the purpose of the rule to have a translator foe the AM stations to serve its COL. But it is what it is I guess.
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Re: AM primary station to Translator separation

Post by Shane »

Works the other way, too. KCRO on 660 in Omaha has a huge 2 mv/m coverage area and has a translator 50+ miles away in Lincoln, which would not have been allowed under the original rule, which was the lesser of the two parameters. I believe it was changed to the greater of the two to allow for highly directional stations to have their translator at the AM transmitter site, primarily.

In the KCRO case, since the translator is still within the 2 mv/m coverage area, it actually does serve to cover an area already covered by the AM station. In the WALI case, it does seem a little hinky since this is a non-D, but it’s legal.

The overarching purpose of the whole idea is to keep AM stations alive (at least so far) and this includes daytimers which can have a nighttime presence by way of the translator(s). And sometimes stations need to have a presence in a city that’s sorta close and larger than the COL in order to do business there and thereby stay afloat (and, we hope, therefore to continue to provide service to said COL, too).
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Re: AM primary station to Translator separation

Post by Deep Thought »

knoxbob wrote: Mon Sep 06, 2021 11:52 am Thank you for the education. To me that kind of defeats the purpose of the rule to have a translator foe the AM stations to serve its COL. But it is what it is I guess.
Oddly enough, that was never the purpose of the rule. It was used by some as the excuse for proposing it but there has never been a CoL coverage requirement for any translator under the current iteration of the rules.
Mark Mueller • Mueller Broadcast Design • La Grange, IL • http://www.muellerbroadcastdesign.com
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