Why do some stations broadcasts at Watts way under their license limit?

[bonton]

I found this board by accident and I see some of yall know the radio biz and can maybe help with this question. Anyone listen to WWOZ while in New Orleans? I read on their website they have a license to broadcast 25,000 Watts but only broadcast 4,000 Watts. Back in the 80s they used all 25,000 Watts but cut back for some reason. I wish they would crank it up a little more to reach more into southern Mississippi.

So the question is, why would a radio station not use all the Watts in their license? Is it a cost issue? If so, what kind of cost per watt are we talking here? You think OZ reaching farther would give them more people for those pledge drives. But that's just one example, I found a few other small market stations broadcasting at watts under their licenses.

 

[Goat Rodeo Cowboy]

When you are struggling each week to scrape up the cash for payroll, and a lot of studio gear needs repair or replacement, and lightning takes out the transmitter, you replace it with a smaller one... just temporarily of course. Sometimes temporary turns out to be 15 years and counting.

Maybe someone else can tell you what the monthly power bill is for a 10,000... 25,000 or 50,000 watt transmitter. I have heard owners report that by trashing their old 1,000 watt tube type transmitter and replacing it with a new solid state transmitter saved enough electricity to pay for the upgrade over just a few years.

 

[Fran]

I am the last person that should be answering your question. But since I am looking for a reason to procrastinate another project. . . let me take a stab at this. 25,000 watt stations have a height limit on how high up they can mount their antenna. So, if their limit is 300 feet, and they mount their antenna higher than that, then they have to cut back on their power. There, you now know my total knowledge of engineering . . . although I might know what HAAT means, but we will save that for another day!

 

[Goat Rodeo Cowboy]

The "history" section of the stations website says they "started with 25,000 watts" in 1980... but no where could I find anything indicating that their CURRENT license authorizes anything but 4,000 watts.

Just reading between the lines, having to re-establish their operation after having to go silent due to Katrina, and operate from temporary studios in Baton Rouge for awhile, I would guess that increasing transmitter power may be way down on their "want list".

Doesn't help you while out driving around maybe, but they are online so you can get a partial fix via your computer.

 

[bonton]

I found this cool website that shows you the license type, power and even map of broadcast range for any radio station. Go to www.radio-locator.com and type in any call letters. WWOZ still has the C3 license for 25,000 watts, but turned the juice down to 4000 watts.

http://www.radio-locator.com/cgi-bin/finder?sr=Y&s=C&call=wwoz

Fran had a good point about the height and that may be the answer. Looks like the C3 license is 300ish feet and their tower is over 500 feet. So looks like the FCC rules have em turn the juice down some.

 

[Goat Rodeo Cowboy]

Now I see where you are coming up with your numbers.  The maximum power that CAN BE licensed for a C3 is 25,000 @ 328 feet.  That does not mean that  WWOZ is LICENSED for 25,000 watts.  That is the maximum they could ask for IF it did not interfere with other nearby stations.

In reading the station's website I believe I saw that their antenna is on top of a downtown building which gives them very good coverage of the city.  Since their antenna is 509 feet above "average terrain" the FCC would limit their maximum power to 10,317 watts, which the FCC would be willing to round up to 10,500 watts.

(10,317 watts at 509 feet should in theory give them exactly the same coverage they would get if they had 25,000 watts at 328 feet.)

We would have to get hold of someone in the WWOZ organization to get an answer to the question as to WHY they have a LICENSE for only 4,000 watts.  Here are my guesses:

1.  They feel the 4,000 watts at 509 feet is giving them the coverage they want.  Any more money spent on a more powerful transmitter and/or a larger electric bill would drain funds they want to spend elsewhere:  Better programming?

2.  The owner of the building on which the tower and transmitter sit has a maximum electrical service limit which would not allow them to power a stronger transmitter at that location. 

(They could achieve higher WATTAGE rating with a larger antenna while keeping a smaller transmitter but that also is costly and may exceed the wind loading permitted by the building.)

3.  There may be another station nearby  (within 150 miles or so) that would received prohibited interference if the power was raised any higher.

I think this conversation has been struggling with the difference between maximum allowable power for any C3 station and what is currently the legally licensed power of this station.

 

[DeadElvis]

WWOZ is over-height. A Class C3, like WWOZ, is envisioned to be 25 kW @ 100 meters (~328'). But, they have chosen to exceed the prescribed tower height and decrease power. There is an equation that determines how much power one is allowed as maximum height is exceeded; I assume WWOZ has run the equation. KKND/102.9 is similarly-situated to WWOZ (though, they have a bit more power and a few feet more height).

I imagine most stations you find with ERP below what is normal fall into this category. There are several reasons for doing this -- certainly, it lowers the power bill. And, in some situations, it might be a good trade-off for coverage. Height is a wonderful thing on VHF.

There are other reasons, too. I see that WWNO is under maximum power for a C1. I wonder if this is due to interference concerns with TV channel 6. One sees that with stations low on the reserve band close to 6s. Of course, TV6 is now dark in New Orleans; that might allow WWNO to increase power.

DE

 

[MN Maniac]

I imagine most stations you find with ERP below what is normal fall into this category. There are several reasons for doing this -- certainly, it lowers the power bill. And, in some situations, it might be a good trade-off for coverage. Height is a wonderful thing on VHF.

Sometimes. Not always.

Once-upon-a-time, I worked for a small group in Kansas. We had one full C and one C1, using a combiner mounted atop a 1,000 foot stick. A few years later, we added a C2. Instead of running the full 50kW at 500 feet, the powers-that-be chose to run 10.5 kW at 900 feet. The tower was located 13 miles from the primary service area.

Result: The C2 could be heard fine on car radios 60 miles away but could not be heard clearly inside the mall or office buildings within the target market. 10.5kW did not have the "oomph" to penetrate the steel and concrete as 50kW would have from the lower height.

 

[Goat Rodeo Cowboy]

A retired consultant proposed that to me about a possible LPFM future application. I was thrilled that my "village target" was nestled up against a 400' mountain. I could go up there and put up something as modest as a telephone pole for a tower and run with 6 or 8 watts of power. No tower to pay for. No long expensive coax cable up the tower. No hungry 100 watt transmitter. Life for a low budget LPFM would be great.

Not so fast said the consultant. Your signal at the base of the mountain, down on the town square, might be so anemic as to be unusable.

Hmmmmmm.

So go downtown. Put up your 100 foot tower. Agitate the electrons with a full 100 watts. Life will be good.

I have found an existing situation within a few hours drive of me where two LPFMs serve a community. One up on a mountain. One down in the valley. I must get up there and walk around town with my Walkman receiver in hand to answer that puzzle once and for all.

 

[DeadElvis]

LPFMs are a different animal, indeed.

The 60 dBu on a LPFM is less than 4 miles. In that case, you want to locate your antenna as close as possible to the exact location you are trying to serve. There can be no waste. Plus, running a 100W transmitter is just not that expensive, and tower space at that height should be plentiful. Cell towers, 10-story buildings*, and even tall trees on hills might work.

Sure, you might get style points for running an 8-Watt station via solar power from atop a mountain. But signal density is a much better prize.

DE

* As an aside, buildings are always the best answer in these cases. Access is easy, and your lossy coax run is short. Heck, run something as cheap as 213; line loss at 20' is just 1/2 dB. Feedline cost? $30. Or buy a scrap piece of hardline off eBay. Loss is trivial.

 

[OKCRadioGuy]

For the most part don't go lower than 1500 watts. Crank the height up. When mountains are in the mix a guy has to worry about multipath issues so the "go higher" part isn't always the best idea. In Oklahoma though it generally makes sense unless you go below 1500 or your so far out of town the station won't work right anyway. Even in the ones that are too far out though overheight is better but nothing can change the laws fo physics lol

 

[OKCRadioGuy]

Also, don't forget downtilt and null fill on tall towered stations. I'm not a big fan of lots of bays for weaker stations either. Do a pattern study on side mounted antennas to put the peer where you want it too. If your on top a nice lambda section on a turnstyle and careful determined placement/orientation can really help.

 

[w9wi]

WWOZ is over-height. A Class C3, like WWOZ, is envisioned to be 25 kW @ 100 meters (~328'). But, they have chosen to exceed the prescribed tower height and decrease power. There is an equation that determines how much power one is allowed as maximum height is exceeded; I assume WWOZ has run the equation. KKND/102.9 is similarly-situated to WWOZ (though, they have a bit more power and a few feet more height).

One can run the equation oneself on the FCC website: http://www.fcc.gov/mb/audio/bickel/fmpower.html. Do that for WWOZ and you get 10.5kw, not 4. Something else is limiting WWOZ, and my guess is that something is KLSA in Alexandria.

Things work a bit differently in the land below 92MHz.

In the 92-108MHz commercial band, to get a permit for a Class C3 station, you have to be able to show a place exists where you could put up a full 25kw/100m station without interfering with anything else. If no such place exists, you can't get a C3 permit. If the most power you can run without interfering with anyone else is 15kw -- well, you can't get a permit for 15kw. You're going to have to settle for a Class A permit, for 6kw.

In the 88-92MHz non-commercial band, you can get as much power as will work without causing interference. If the most you can run without interfering is 15kw, you can get 15kw. Because 15kw is "too much" for class A and "not enough" for Class C2, the FCC will classify you as a C3.

I think WWOZ did the math, for how much power they could run without interfering with any other existing stations, and the answer they got was 4kw. That's what they filed for, that's what the FCC granted. And because that's too much for Class A (the Class A limit at 155m antenna height is about 2.9kw) and not enough for Class C2 (the C2 minimum at 155m is 10.5kw) they got classified C3.

I haven't done the math on this but a quick look at the database shows a 100kw NPR station on the same frequency as WWOZ in Alexandria in the center of Louisiana. My guess would be this station is the limit on WWOZ's power. I would not rule out the possibility that WDSU-TV channel 6 might be the limit as well. The analog TV-6 signal may no longer exist, but the FCC only began taking applications that conflicted with TV-6 in the last couple of weeks. I don't see any sign that WWOZ has applied, but the application may not have made it through the FCC bureaucracy yet.

I think KKND is a "73.215 short-spaced station". (probably with regard to 95kw KAJN-FM in Crowley) To get a C3 permit you have to be able to show a place exists where you could put up a full 25kw/100m station without interfering with anything else. But you don't actually have to build your station at that place. You can build somewhere else, closer to the existing station you're trying to avoid interfering with, if you reduce your signal in the direction of that station enough to avoid interference.

Usually this is done with a directional antenna. However, it looks like KKND's licensed operation is doing this by simply reducing power. They're licensed for 4.7kw; the ordinary maximum for a C3 at 184m is 7.2kw. I also note KKND has a permit to reduce antenna height to 121m, increase power to 17.5kw, and install a directional antenna. 17.5kw is the Class C3 maximum for a 121m antenna, and the directional antenna has a null to the west -- exactly where Crowley is.
_________________________________________________
I can't find any evidence WWOZ has any kind of permit to make any kind of technical changes. I can't even find an *application* to make changes.

 

[Doctor_Technical]

My understanding/memory is that WWOZ's downtown tower site (and thus their antenna height and the resultant ERP) is where it is for a more mundane reason: a great site became available.

Before the construction of the 1000' Lodestar/Spectrasite/ATC/"Your_Name_Here" master antenna on the west bank, 93.3 and 97.1 broadcast from a pole located on top of the Tidewater Building on Canal Street. Each station had their own ~12-bay antenna; one was on one side (face) of the pole, the other on the opposite side. All of those bays located on a big rooftop pole was an impressive sight, especially since the guyed pole was/is right next door to 990 AM's self-supporting tower located on the rooftop of the Jung/Radisson/"You_Don't_Want_Your_Name_Here" Hotel (which may be torn-down due to Katrina damage, meaning bye-bye to one of the last rooftop AM towers in the country. But that's another story).

After moving to Lodestar, WQUE and WEZB pulled their bays off the Tidewater site, but the pole remained. And there moved WWOZ, to the top of the now-empty pole. Sure it's "only" 4KW, but at 500' above the geographic center of a very densely populated city and area (at least south of the lake), it was a darn smart move.

 

[scottwmro]

I found this board by accident and I see some of yall know the radio biz and can maybe help with this question. Anyone listen to WWOZ while in New Orleans? I read on their website they have a license to broadcast 25,000 Watts but only broadcast 4,000 Watts. Back in the 80s they used all 25,000 Watts but cut back for some reason. I wish they would crank it up a little more to reach more into southern Mississippi.

So the question is, why would a radio station not use all the Watts in their license? Is it a cost issue? If so, what kind of cost per watt are we talking here? You think OZ reaching farther would give them more people for those pledge drives. But that's just one example, I found a few other small market stations broadcasting at watts under their licenses.

I have one simple answer for all of you, the economy stinks and stations are not making the money they once were.

 

[CatFM]

Financial considerations are very likely in some cases, but that is nothing new with the current economy. The first station I worked for had an FM licensed for 27 KW, but we only ran 25. We had an old RCA xmtr, and the story I heard was that part of the amplifier section of it was in the GM's garage because it didn't work, which is why we couldn't achieve full power. He didn't feel the loss of 2 KW ERP was enough reason to spend any money to have it fixed. We logged the actual power, so I don't know how legal it was, but that is how we operated for the two years that I worked there. For historical perspective, that was in the mid 70s.

On the AM side, XEROK Juarez operated in the late 70s with 50 KW during the day instead of their licensed 150 KW. They had the Mexican equivalent of an STA to operate with reduced power during the day because they were trying to work on some ground system problems. I visited the station in early 1978 while they were operating that way and the insiders told me that while the ground system really was the reason in the beginning, they were dragging it out as long as possible because the electric power on the Mexican side of the border was so expensive, and that extra 100 KW during the day didn't improve their ground wave signal enough to make it worthwhile since there aren't that many people out in the desert to hear it. They kicked it back up to 150 KW every night at sunset to take advantage of their big skywave signal, but the day signal stayed at 50 KW to keep the electric bill lower. I was told they even looked into running a generator at the xmtr site because the power was so expensive. Anyway, the last I knew, XEROK was still operating with 50 KW day, even though they are licensed for 150 KW fulltime.