VHF TV Propagation in Phoenix

[landtuna]

The first strong storm of the monsoon season arrived evening before last and gave me a chance to test out the latest antenna setup.

The storm hit my neighborhood right when the evening news began and immediately the Big 3 UHF stations pixelated into nonsense. I quickly turned to VHF 12 and got an almost perfect picture. Trying VHF 8 and 10.2 gave me a picture on 10.2 but 8 never dropped in at all. 10.1 is also useless in a storm (but in all fairness it was raining very heavy at the time).

The antenna in use is a 20-year old combo FM/VHF/UHF about 12 feet AGL and pointed right at South Mountain (about 8 miles as the crow flies). This same antenna was used in the pre-digital days from far north Phoenix (I-17 and Happy Valley Road) in my attic no less and I could receive everything. That was about a 30-mile distance and there was significant foil insulation inside the attic.

I think if the federal gubmint makes another dismal decision regarding OTA TV I am just going to trash every antenna I have and go internet streaming. I don't watch so much TV that a scheme like that won't work.

 

[KeithE4]

The first strong storm of the monsoon season arrived evening before last and gave me a chance to test out the latest antenna setup.

The storm hit my neighborhood right when the evening news began and immediately the Big 3 UHF stations pixelated into nonsense. I quickly turned to VHF 12 and got an almost perfect picture. Trying VHF 8 and 10.2 gave me a picture on 10.2 but 8 never dropped in at all. 10.1 is also useless in a storm (but in all fairness it was raining very heavy at the time).

The ERP of the three VHF stations (8, 10, and 12) is too low. Per rabbitears.info, Channel 8 runs 40 kW ERP, which is roughly equivalent to 80 kW analog video. Channel 10 runs 48 kW ERP, and Channel 12 runs 39 kW ERP.

To have coverage equivalent to the 316 kW ERP of the analog days, VHF-HI stations would need to run about 153 kW ERP. BTW, Channel 10.2 airs via KUTP, which is UHF.

The antenna in use is a 20-year old combo FM/VHF/UHF about 12 feet AGL and pointed right at South Mountain (about 8 miles as the crow flies). This same antenna was used in the pre-digital days from far north Phoenix (I-17 and Happy Valley Road) in my attic no less and I could receive everything. That was about a 30-mile distance and there was significant foil insulation inside the attic.

Your antenna is fine. It may even be too much. Your receivers may be overloading, which will kill the picture. Also, do you have an FM trap in your line, before the preamp (if you have one)? As close as you are to South Mountain, those dozen or so 100 kW FM sticks will overload just about everything you have.

When I lived in Ahwatukee (5 miles from the towers), I found that adding an FM trap before the preamp was the difference between watching and not watching most of the stations, both VHF and UHF. Doesn't make much of a difference out here in NE Mesa (25 miles away, and 400 ft higher in elevation than downtown Phoenix). But rabbit ears won't work here on VHF. I have a small outside antenna with a preamp that works perfectly well, at least on all the full-powered stations and Channel 7. The other LPTV/Class A stations are iffy at this distance.

I think if the federal gubmint makes another dismal decision regarding OTA TV

We'll see what ATSC version 3 does. Multipath is just as much an issue, if not more, with version 1 as low power is, and that's supposed to be fixed. I live in the flight path for Falcon Field, and planes killing signals is a regular thing. It doesn't matter if the plane is a single-engine Cessna or a restored B-19 from the Commemorative Air Museum; when planes fly over my house, signals go away. Heavy clouds also cause multipath, but it has to rain pretty heavily (no issues the other night) to kill reception. But that's true for DirecTV as well.

I am just going to trash every antenna I have and go internet streaming. I don't watch so much TV that a scheme like that won't work.

That is exactly what the broadcast stations want you to do. They'd turn those expensive, high-maintenance transmitters off if the FCC would allow it. They make almost no money from OTA, other than a small percentage of the ad dollars. Advertising alone won't support a bloated news staff and an overabundance of local news and features programming, especially on two-station facilities (3/5, 10/45, 15/61 soon). This isn't the 1950s, and the advertising-only business model failed years ago.

 

[landtuna]

To have coverage equivalent to the 316 kW ERP of the analog days, VHF-HI stations would need to run about 153 kW ERP. BTW, Channel 10.2 airs via KUTP, which is UHF.

Something about 10.2 is definitely different as the PQ looks like the old analog signal and it comes roaring in when 10.1 is trash.

Your antenna is fine. It may even be too much. Your receivers may be overloading, which will kill the picture. Also, do you have an FM trap in your line, before the preamp (if you have one)? As close as you are to South Mountain, those dozen or so 100 kW FM sticks will overload just about everything you have.

No preamp and no FM trap either. I do have a signal splitter than feeds my FM receiver from the same antenna. I never listen to that receiver though so might try un-splitting and installing an FM trap.

We'll see what ATSC version 3 does. Multipath is just as much an issue, if not more, with version 1 as low power is, and that's supposed to be fixed. I live in the flight path for Falcon Field, and planes killing signals is a regular thing. It doesn't matter if the plane is a single-engine Cessna or a restored B-19 from the Commemorative Air Museum; when planes fly over my house, signals go away. Heavy clouds also cause multipath, but it has to rain pretty heavily (no issues the other night) to kill reception. But that's true for DirecTV as well.

I remember living in Tucson near Davis-Monthan AFB and having those same issues back in the 50's. What's old is new again, eh?

That is exactly what the broadcast stations want you to do. They'd turn those expensive, high-maintenance transmitters off if the FCC would allow it. They make almost no money from OTA, other than a small percentage of the ad dollars. Advertising alone won't support a bloated news staff and an overabundance of local news and features programming, especially on two-station facilities (3/5, 10/45, 15/61 soon). This isn't the 1950s, and the advertising-only business model failed years ago.

Based upon your statement it seems to me it would be better technically and financially to just stream TV signals these days and abandon OTA all together. That would leave many rural viewers in the dark as their internet options are not as robust as those of us in the metro areas. Of course TV reception is not a Constitutionally protected right if you choose to live in Jasper Junction.

 

[KeithE4]

Channel 10.2 is SD, 480i. The only HD subchannel on KUTP is 45.1.

 

[KeithE4]

Based upon your statement it seems to me it would be better technically and financially to just stream TV signals these days and abandon OTA all together. That would leave many rural viewers in the dark as their internet options are not as robust as those of us in the metro areas. Of course TV reception is not a Constitutionally protected right if you choose to live in Jasper Junction.

First of all, the internet backbone is not ready yet, and won't be for several more years. Even my 80 Gb CenturyLink connection bogs down when there's more than two video streams going at once.

Second, for those who get their internet from cable companies like Comcast and Cox, there could be a conflict of interest. They're in the business of selling cable TV, and might not like their customers connecting to YouTubeTV, Netflix, and the others. AFAIK, they don't block or throttle back these services right now, but since SCOTUS said it's OK for them to do so (no more Net Neutrality, at least for now), who knows what the future lies.

Third, it's highly unlikely that a "fat enough pipe" for streaming TV will ever be installed in Rural America. It's just not cost effective. Look how long it took for dial telephone service, let alone direct long distance dialing, to finally cover the country. The big cities started having it pretty much as soon as it was invented, about 100 years ago. It took about 50 years to give dial service to all of the small towns. I think a similar time-frame for super-speed internet in the rural areas will prevent the FCC from shutting off broadcast TV. Especially if what AT&T/DirecTV says becomes reality, and the satellites begin to fail in the next decade or so. In fact, I think we'll see even more translators in the future, instead of shutting them down like Canada's doing.

 

[Prescott Joe]

Quote from Landtuna:
"The antenna in use is a 20-year old combo FM/VHF/UHF about 12 feet AGL and pointed right at South Mountain (about 8 miles as the crow flies). This same antenna was used in the pre-digital days from far north Phoenix (I-17 and Happy Valley Road) in my attic no less and I could receive everything. That was about a 30-mile distance and there was significant foil insulation inside the attic."

You do not mention what is between your antenna and South Mountain antennas. Nearby trees and other obstructions cause the exact kind of
issues you describe. Any antenna that is 20 years old is well beyond it's service life. Another possibility is a deterioration of the plastic insulators
caused by attic heat and Arizona Sunshine. I suggest you consider the above before condemning the engineers at Phoenix television stations......
Channel Master still offers the old style VHF/UHF/FM antennas you need as well as the Winegard 7694p.

 

[landtuna]

Quote from Landtuna:
"The antenna in use is a 20-year old combo FM/VHF/UHF about 12 feet AGL and pointed right at South Mountain (about 8 miles as the crow flies). This same antenna was used in the pre-digital days from far north Phoenix (I-17 and Happy Valley Road) in my attic no less and I could receive everything. That was about a 30-mile distance and there was significant foil insulation inside the attic."

You do not mention what is between your antenna and South Mountain antennas. Nearby trees and other obstructions cause the exact kind of
issues you describe. Any antenna that is 20 years old is well beyond it's service life. Another possibility is a deterioration of the plastic insulators
caused by attic heat and Arizona Sunshine. I suggest you consider the above before condemning the engineers at Phoenix television stations......
Channel Master still offers the old style VHF/UHF/FM antennas you need as well as the Winegard 7694p.

Thanks for the suggestions on the new antennas but the old one is still in fine shape. No hint of plastic insulators cracking and all elements are in their original position. Remember, this antenna was in a ventilated attic for much of its service life so no excessive heat, weather or sun.

There are no obstructions between my antenna location and South Mountain antenna farm. Clear shot, about 8 miles as the crow flies.

And I was not aware I was condemning the TV engineers. I was criticizing the shortcomings of digital TV.

 

[KeithE4]

No preamp and no FM trap either. I do have a signal splitter than feeds my FM receiver from the same antenna. I never listen to that receiver though so might try un-splitting and installing an FM trap.

Since you don't have a preamp, you can connect an FM trap between the splitter output and the TV, leaving the FM side alone.

 

[dhett]

There's nothing wrong with the full-power Phoenix stations. Any of them.

 

[landtuna]

There's nothing wrong with the full-power Phoenix stations. Any of them.

Prior to the digital conversion I would have agreed with you.

 

[KeithE4]

Prior to the digital conversion I would have agreed with you.

But they ran either at or close to the full 316 kW allowed at VHF-HI on analog.

 

[Prescott Joe]

Running at or near full F.C.C. allotted power is not an assurance of good reception
at the user end. Overload, harmonics, and other factors need to be considered.
I've received stable, consistent, reception of Rf 8, 10 and 12 on South Mtn from
Prescott Valley. Some of the UHF stations also can be received in Prescott Valley,
but not as reliably. When having reception problems, the persons receiving equipment
needs to be properly performing before placing blame on the transmitting side.
I cannot help but laugh when I hear of issues close to full power antenna farms. Try places
like Seligman, Chino Valley, Show Low, Ash Fork for real reception issues!!!!!!!!!!

 

[dhett]

Prescott Joe is right: the problem is on the receiving end.

If it were on the transmitting end, I'd be having problems too.