Over-powered translator

FM does it with frequency!
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NECRAT
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Over-powered translator

Post by NECRAT » Sat Oct 21, 2017 7:38 am

So somewhat nearby me, a translator for a foreign language AM station signed on. However I have pretty solid reason to believe they are way over power. Knowing the terrain, other co-located stations, and other nearby signals, this one signal really gets out well. Better than a class A in the next city over. Is there any way for me to determine if the translator is running over-power, short of having the engineer show me the transmitter setup.
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Re: Over-powered translator

Post by fm-engineer » Sat Oct 21, 2017 8:23 am

What is the HAAT? A little known loop-hole in AM to FM translators: there is no maximum height restriction or ERP reduction with 250 watts. In other words, you can transmit 250 watts at unlimited height as long as there is no interference with protected FM stations, and it falls within the normal service contour of the AM station. Other classes must reduce ERP when exceeding permitted height (usually 100 or 300 meters).

There are many new AM translators performing as well or better than some Class A stations.

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Re: Over-powered translator

Post by NECRAT » Sat Oct 21, 2017 9:50 am

Around 102 m at 99 watts. The terrain around it to the south is pretty flat, but to the north, it gets quite hilly.
It's also semi directional as well. Just seems to get out much much much better than it should.
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Jim Sofonia
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Re: Over-powered translator

Post by Jim Sofonia » Sat Oct 21, 2017 10:54 am

Sometimes you can get an idea whats going on by looking at the electric meter.

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Re: Over-powered translator

Post by TPT » Sat Oct 21, 2017 12:08 pm

Maybe... Recently added a Class A tenant to one of my sites, electric bill only went up about $100. They are running a VS-1 at around 800 watts for 750 radiated. They were supposed to install their own power feed, but that's been delayed since the electric company has so many crews doing emergency work down south--so I've been watching power consumption as best I can. My station's transmitter draw is steady at around 10 kw, but HVAC costs become the wild card.

Oh, and FM translators for AM stations just have to keep their 60 dbu inside a 25 mile circle from the AM tower.

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Re: Over-powered translator

Post by Deep Thought » Sat Oct 21, 2017 10:19 pm

If you have a field intensity meter handy measure the FX in the major lobe at around 1-2 miles and then another station at the same distance. The near-field propagation should be similar and you can directly compare the measurements to get a rough idea of what the actual ERP is.
Mark Mueller • Mueller Broadcast Design • La Grange, IL • http://www.muellerbroadcastdesign.com

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Re: Over-powered translator

Post by musiconradio.com » Sun Oct 22, 2017 1:05 pm

Height is the Key. We have several translators that are above 200+M above sea level mark ranging from 10W to 75W overlooking the city. Their signals are good as a Class A. There are two 250W on the the hill (one is directional). The are all running legal power, but get out extremely well.

What the coverage map says Vs, actually coverage can be a big difference and still be legal.

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Re: Over-powered translator

Post by Deep Thought » Sun Oct 22, 2017 3:46 pm

musiconradio.com wrote:
Sun Oct 22, 2017 1:05 pm
The are all running legal power, but get out extremely well.

What the coverage map says Vs, actually coverage can be a big difference and still be legal.
The coverage map only depicts the artificial protected service contour, which no radio has a concept of; it's just an allocation tool. You may very well "get out" (what is this, CB Radio?) fine to the 25 or 50 uV/m signal level (28-34 dBu) in the absence of co- and first-adjacent-channel interference but that doesn't tell you anything about the performance of the transmit antenna, just that of the receiver. In fact, it may "get out" fine on your radio while still being +/- 6 to 12 dB off of what it is supposed to be signal-wise. This is why testing is important. Your "legal" translator may be anything but and is a sitting duck for an interference complaint.
Mark Mueller • Mueller Broadcast Design • La Grange, IL • http://www.muellerbroadcastdesign.com

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