AM primary station to Translator separation

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Ray
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Joined: Sat Mar 22, 2014 10:04 am

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.
TPT
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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
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