A Super LPFM? Just playin' with the numbers

[mofocat]

LPFMs are limited to 100 watts @ 30m HAAT. Height Above Average Terrain being the key variable.
OK, so put the antenna at the edge of the foothills, where the hills increase the average elevation. Such as where the KMJ 4 tower array sits. ( Approx. 36* 39' 30" / 119* 20' 46")

At that location 30 meters above AVERAGE terrain is actually about 120 m, or 380 FEET, above the flatland ground level where the population is. According to the REC Networks LFM Search site. That's only half way up on one of those 800ft. KMJ towers.

How far will 100 watts go from 380 ft.? A lot farther than from 100ft. I would assume. Far enough to reach Reedley, Sanger, Dinuba, Orange Cove with 50+dbu Very interesting. A Rice Longly plot shows 50dbu getting to the south edge of Visalia, as I remember. (It's been a year since I ran the figures.)

Just playin' with the numbers. I would hope there could be some creative application of the LPFM opportunity to come. But, sadly, not expecting much to happen around here.

 

[davideduardo]

How far will 100 watts go from 380 ft.? A lot farther than from 100ft. I would assume. Far enough to reach Reedley, Sanger, Dinuba, Orange Cove with 50+dbu Very interesting. A Rice Longly plot shows 50dbu getting to the south edge of Visalia, as I remember. (It's been a year since I ran the figures.)

But keep in mind that 65 dbu is pretty much the extent of the usable in-home and at-work signal.

 

[radioboy]

Also, as the height increases, the wattage amount decreases, so it is likely there will be less than 100 watts to play with.

 

[MisterGort]

The only FM channel that might work - without an FCC waiver is 104.7. That said -- what COL - City of License would be within 5.6 KM of the tower location ? And would you -- the applicant live within a 10 mile radius of that tower location ? What would the POP-Count be from that site ?? Would KMJ even rent that tower to anyone ? What would you have to pay for rent ?? Maybe $ 1,000 a month rent ? How musch would it cost to construct - even a LPFM from that location - or site on the side of the hills ? Where is the cash going to come from ? Wish you luck - put it seems to be a LPFM Money pit.

 

[mofocat]

Also, as the height increases, the wattage amount decreases, so it is likely there will be less than 100 watts to play with.

Alan, being that you are in FLA, I guess, explains your missing the concept of HAAT. Locations with nearby hills or mountains tend to have higher AVERAGE terrain elevations, whether you are on top of the hill/mountain or on the flat land nearby. Therefore, to get to a specific HEIGHT ABOVE the AVERAGE, you have to go higher.

 

[mofocat]

The only FM channel that might work - without an FCC waiver is 104.7. That said -- what COL - City of License would be within 5.6 KM of the tower location ? And would you -- the applicant live within a 10 mile radius of that tower location ? What would the POP-Count be from that site ?? Would KMJ even rent that tower to anyone ? What would you have to pay for rent ?? Maybe $ 1,000 a month rent ? How musch would it cost to construct - even a LPFM from that location - or site on the side of the hills ? Where is the cash going to come from ? Wish you luck - put it seems to be a LPFM Money pit.

The city of license for an LPFM does not have to fall into the 60dbu contour. The population within the 50 dbu is easily over 100,000.

Hold on everyone, I did not say I was interested in filing on this- I was just noting the technical parameters that allowed the full 100 watts ERP @ 380ft.
Would KMJ allow a small FM antenna to be mounted on one of it's towers? Probably not. However if the Gen. Mngr. of KMJ wanted to do something for her home town of Reedley, by allowing an antenna for a Reedley based non-profit-civic organization. Maybe Reedley College could be the licensee. I do believe said KMJ mngr has familial ties there beyond simply being a former student. Donated tower space could be a tax advantage to KMJ.
A station doing hyper-local community involvement not available on any other station will have higher than average numbers of listeners that make an effort to tune a signal below the 65dbu level.

 

[kenrayc]

The only FM channel that might work - without an FCC waiver is 104.7. That said -- what COL - City of License would be within 5.6 KM of the tower location ? And would you -- the applicant live within a 10 mile radius of that tower location ? What would the POP-Count be from that site ?? Would KMJ even rent that tower to anyone ? What would you have to pay for rent ?? Maybe $ 1,000 a month rent ? How musch would it cost to construct - even a LPFM from that location - or site on the side of the hills ? Where is the cash going to come from ? Wish you luck - put it seems to be a LPFM Money pit.

I think you mean 104.5, as 104.7 is KHTN Merced, and already has a decent signal in Fresno, I think 92.5 or 100.7 are good possibilities as well, but I believe a commercial LPFM must simulcast an AM and can't extend the AM signal, how about KYNO-FM 92.5.

 

[mofocat]

The only FM channel that might work - without an FCC waiver is 104.7. That said -- what COL - City of License would be within 5.6 KM of the tower location ? And would you -- the applicant live within a 10 mile radius of that tower location ? What would the POP-Count be from that site ?? Would KMJ even rent that tower to anyone ? What would you have to pay for rent ?? Maybe $ 1,000 a month rent ? How musch would it cost to construct - even a LPFM from that location - or site on the side of the hills ? Where is the cash going to come from ? Wish you luck - put it seems to be a LPFM Money pit.

I think you mean 104.5, as 104.7 is KHTN Merced, and already has a decent signal in Fresno, I think 92.5 or 100.7 are good possibilities as well, but I believe a commercial LPFM must simulcast an AM and can't extend the AM signal, how about KYNO-FM 92.5.

There is no such thing as a commercial LPFM - all LPFMs must be non-commercial. You are thinking of translators, which MUST re-broadcast other stations, traditionally FMs, but now, they can be used to re-broadcast either AM or FMs.
yes it is 104.5 that is available for lpfm in the area.

 

[DanielBoone]

KDJK 103.9 is a low powered, at only 71 watts but stretches pretty good: Los Banos, Dos Palos, Firebaugh, Mendota and Kerman. I know a big reason is the 4,200 feet in elevation, so that helps a lot. It used to boom into Fresno pretty good, but, like Paul Harvey said, "You know the rest of the story."

 

[mofocat]

KDJK 103.9 is a low powered, at only 71 watts but stretches pretty good: Los Banos, Dos Palos, Firebaugh, Mendota and Kerman. I know a big reason is the 4,200 feet in elevation, so that helps a lot. It used to boom into Fresno pretty good, but, like Paul Harvey said, "You know the rest of the story."

KDJK and KMAK have very similar transmission parameters in regards to power, HAAT, and actual height above sea level, but they are not LPFMs. They are class A FMs. LPFMs are an entirely different class of license.

Class As: Max power 6kw ERP @ 100m HAAT - power reduces as antenna height increases above 100m above average terrain
LPFM: Max power 100 watts @ 30m HAAT - power reduces as antenna height increases above 30 meters above average terrain.
Big difference.
There are only four Class As in Fresno area: KFSR 90.7 @ FSU; two in Kerman, 94.3 and 95.3; and KMAK,100.3.
There are currently no LPFMs locally, the closest being in Visalia, Tulare, Merced, Dos Palos, Lemoore.

The FCC will be taking applications in the fall for possibly 2 to 4 potential LPFMs to be established in Fresno area. These are NON-COMMERCIAL licenses limited to the 100w @ 30m LPFM parameters. (Not enough signal to cover the entire city)

 

[DanielBoone]

Thanks for telling me this.

 

[brettbutlerisok]

KGAR in Lemoore seems to do about 15 miles from the tower well in my car. When I lived at 14th and Grangeville I could pick it up in my house but very scratchy.

Bad thing about LPFM you can't make any money. Back in the day I worked with some guys who brokered time on 1400 out of Visalia doing mostly community programming. They always managed to sell enough spots to pay for the air at the least. It lasted all they way until CC started simulcasting 1340 instead of 92.9

Maybe KJUG-AM, KIRV, or KIGS, is where I would start if I still had the time, energy, or drive.

 

[MisterGort]

The only OPEN or Clear frequency for use at or near the KMJ AM towers -- for LPFM is 104.7 -- NOT 104.5. I did a frequency staudy for LPFM. There are 9 other frequencies - but all of the of those require an FCC waiver. You can even check the FCC LPFM site to find the same frequency.

KMJ -- is bankrupt. They do NOT need a tax deduction of any tax type. Nor would any LPFM provide coverage to any population close to 50,000 persons. Maybe 25,000 at very most. LPFM maximum power is 100 watts at Plus 30 Meters HAAT. KMAK is a class AO (old class A - 3 KW + 100 Meters HAAT) An LPFM from the KMAK site on Bear Mtn would be limited to about 3 watts.

 

[mofocat]

Well I ran the numbers again. 100 watts at 30m HAAT at 36* 39' 30" / 119* 20' 46" (KMJ site) Rice-Longley shows the 60dbu contour encompassing or touching the city limits of Orange Cove, Reedley, Dinuba and Sultana. I know this area like the back of my hand, I grew up there. As a teenager in the 60s I helped plant hundreds of acres of orange trees from Navelencia to Yetem. LOL Including the trees that were pulled out to plant the KMJ towers at Cove and American Aves. That 60dbu contour easily encompasses a population of 50,000+. At 55dbu, not an unreasonable signal level for a rural area, Sanger is included, another 25,000. These population numbers are just the inside city limits population. Easily there are 25,000 more not included in the city population numbers. Having intimate knowledge of this very localized area, I can safely say there is easily a population of 75,000 within the 55dbu contour of the theoretical 100 watts at 30m HAAT at 36* 39' 30" / 119* 20' 46" (KMJ site).

 

[mofocat]

Location! Location!! Location!!! Getting close to or on the foothills can have a huge effect. As the HAAT increases, the LPFM antenna gets to be placed higher before a reduction in ERP is demanded.

Another example. My old homestead. on flat ground east of Orange Cove but only 1 mile from first foothills. Already, the flat land is @ 380ft elv - 100 feet higher than it 20 miles to the west. Then the hills to the east increase the HAAT dramatically. At the old homestead, being on flat ground but already higher than the ground to the west, I would have to mount my LPFM antenna on a tower more than 170 meters tall (544 feet) before I would have to reduce power below the 100 watts max for LPFMs! Plot that on Longley-Rice!

OK OK we're not talking about a Class A or anything, but this is not your generic 30 meter high/100 watt LPFM. And nobody is going to put up a 544' tall tower for an LPFM! Of course not! BUT my old neighbor a mile north of that location DOES have a 500 ft. hill on his property. The 50 dbu Longly-Rice contour encompasses an arc from Sanger to the north boundary of Visalia. 100w @ 30m above ground level is not going to do that.
Just to make the point that the HAAT /ERP equation can be used to great advantage in the right geographic location. Hills and mountains on the back side of your antenna location can be a huge advantage - IF there is population close enough. Take andvantage of the increasing HAAT by just going high enough to NOT have to reduce ERP. Kinda like KJUG and KCRZ did in jumping off of Blue Ridge.

 

[MisterGort]

Ok -- so where is this 500 foot hilltop ? Co-ordinates please.

 

[mofocat]

Ok -- so where is this 500 foot hilltop ? Co-ordinates please.

Could be one of any of the foothills North and East of Orange Cove.

 

[MisterGort]

Ok -- so you only have 94.3 and 104.7 -- listed as open or available for use northeast of Orange Cove. And both have full power FM's on them. The heck with any Longley-Rice contour. You would get out about 5 miles and that would be it.

Try using the FCC Low Power channel study. Se what channels you can locate that might work.

I think the idea is good - but not a real project to build and operate.

 

[kenrayc]

Ok -- so you only have 94.3 and 104.7 -- listed as open or available for use northeast of Orange Cove. And both have full power FM's on them. The heck with any Longley-Rice contour. You would get out about 5 miles and that would be it.

Try using the FCC Low Power channel study. Se what channels you can locate that might work.

I think the idea is good - but not a real project to build and operate.

104.5, 92.5, 100.7 and 98.5 would work better, there's no stations on those in that area ( more than 70 miles at least), co-channel interference would kill 104.7 and 94.3 to the West and North.

 

[MisterGort]

Yes - both 94.3 and 104.7 would get some very bad IF from both Co-channel and adjacent channel stations. However --those two frequencies are the ONLY two open available channels to the North-east area of Orange Cove. Any other FM channel would NOT work.
It is not going to happen. So dream on all you fools.