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Seattle-Tacoma Area AM groundwave coverage - Crummy in spots.

R

RF101

Two major components impact Puget Sound AM stations' coverage. On the positive the Sound's waterways provide great signal paths with little loss. On the downside, the dominant glacial till soils and underlying rocks offer poor conductivity. Once a listener leaves the shoreline areas then reception falls apart. (We're not in Kansas anymore .. nor even the Dakotas, Iowa, Nebraska, etc.)
I see this as evidence in all the 2 mV/m primary contours from the monster 50 kw stations. The stations at the top ends of the dial really suffer. Just look at non-directional KKMO 1360 Tacoma's.

Question - Several of the AM contours are missing from the FCC's KML file set, particularly, KIRO 710's . I would love to see their 2 mV/m and 0.5 mV/m contours. Does anyone have a (KML) source for them ?
 
It's the KIRO AM 710 flamethrower that's big void. Some of the KML archives failed to transition to the new system. Oh yes, KKMO is interesting as it is one of the few non-directional AMs in the area with any sort of reach..
 
RF101 said:
Two major components impact Puget Sound AM stations' coverage. On the positive the Sound's waterways provide great signal paths with little loss. On the downside, the dominant glacial till soils and underlying rocks offer poor conductivity. Once a listener leaves the shoreline areas then reception falls apart. (We're not in Kansas anymore .. nor even the Dakotas, Iowa, Nebraska, etc.)
I see this as evidence in all the 2 mV/m primary contours from the monster 50 kw stations. The stations at the top ends of the dial really suffer. Just look at non-directional KKMO 1360 Tacoma's.

Question - Several of the AM contours are missing from the FCC's KML file set, particularly, KIRO 710's . I would love to see their 2 mV/m and 0.5 mV/m contours. Does anyone have a (KML) source for them ?
Click to expand...

the top end of the dial does great up here.. and not just because of the pattern.

The most consistent AM for me up here is a pretty close tie between 1380 and 1520.... but 1380 wins if you take into account I often hear KOKC under KKXA after KOKC went back to 50kw night

The one surprising AM, in a way, is KKMO.. it is consistently listenable with 5kw at 1600 miles because of it's tower location on the water

 
SomeRadioGuy said:
the top end of the dial does great up here.. and not just because of the pattern. The most consistent AM for me up here is a pretty close tie between 1380 and 1520.... but 1380 wins if you take into account I often hear KOKC under KKXA after KOKC went back to 50kw night

The one surprising AM, in a way, is KKMO.. it is consistently listenable with 5kw at 1600 miles because of it's tower location on the water
Click to expand...
I'm always amazed at what signals get up to Alaska. And Paul is not near the coast. These signals might travel over water for part of their journey but also over land... unless it's all skywave. But then, if it were skywave, having the transmitters near Puget Sound wouldn't make a difference. So I guess it's a combination of the two.
 
RF101 said:
Yes, I saw those maps as well. Unfortunately , the 2 mV/m contours are not part of drawings - perhaps the 0.5 and (maybe) 1.0 mV/m. It's the 2 mV/m and 0.5 that are normally found in the FCC KML archives.
Click to expand...
I did some comparisons using several Seattle-area AM signals. The inner contours shown on the AM DXers maps did not line up with the 2.0 mV/m in any cases. Like I said, perhaps 1.5 or 1.0..
 
You brought up an interesting point. While I’ve never lived on Vashon Island, I grew up not far from the island. I’m used to getting a ridiculously strong signal from most of the major AM stations in Seattle. I consider any station broadcasting from Vashon to be the “gold standard” for coverage in the metro.

I put KIRO 710 and KNWN 1000 at the top of the pyramid. I’ve never had any issue picking up a strong signal from both Class As around the market. KJR 950 and KVI 570 are also very good. Despite being 5kw, KVI sounds crystal clear (thanks to dial position, I would assume). 820 is also fine.

770 and 1090 both are fine during the day, but struggle at night. It’s workable, but far from ideal. I think the same can be said for KIXI on 880.

Outside of the stations above, it gets pretty touch and go. A lot of smaller AMs are mixed in, but none that cover the entire market effectively. KKMO isn’t that bad, but it’s not “full market.”

And as a side note, even if AM is challenging in Seattle, I think it’s even more challenging in my current city (Vancouver). The AM stations here don’t seem to get out very well. It was probably okay 40 years ago, but with an expanding population to the east of the transmitter sites (and little power being directed east), there are some pretty big holes.
 
RF101 said:
Yes, I saw those maps as well. Unfortunately , the 2 mV/m contours are not part of drawings - perhaps the 0.5 and (maybe) 1.0 mV/m. It's the 2 mV/m and 0.5 that are normally found in the FCC KML archives.
Click to expand...
And none of those are of any use today. The ITU says 15 mV/m is the needed minimum for urban area AM reception. I think that is a bit high, but it is certainly around 10 mV/m or higher.
 
Agreed.. Yes..The ambient RF noise has really gone to extremes..motors, computers, eco-friendly lighting, etc.

The 2.0 mV/m contour is used by the FCC for determining if an AM signal qualifies as a fill-in audio source for an FM translator.. This figure may exceed the 40 km normal limit...
 
Gregg. said:
I'm always amazed at what signals get up to Alaska. And Paul is not near the coast. These signals might travel over water for part of their journey but also over land... unless it's all skywave. But then, if it were skywave, having the transmitters near Puget Sound wouldn't make a difference. So I guess it's a combination of the two.
Click to expand...
I think I remember Paul stating that he gets zero daytime am signals which would lend to it being all skywave.
 
Michael Rivers Kramer said:
I think I remember Paul stating that he gets zero daytime am signals which would lend to it being all skywave.
Click to expand...
I wonder what the record for groundwave coverage is?

I know from DXing days that we'd occasionally find a very distant station coming in at around noon. At Cleveland, OH, around 1961 I got 4VEH from Cap Hatien, Haiti, on 1035 kHz with a readable by very weak signal. Of course, being on a "split" frequency made this possible. Otherwise, my best is listening to WBZ in Boston somewhere off Georgetown in the Bahamas on a sailboat with no electronics turned on... could have been ground-wave, but was also around noon and the closest other signal on 1030 was a directional operation in Puerto Rico,
 
I’ve heard KFBK here in the LA area in the late morning, but it was winter and I just chalked it up to late occurring skywave due to the sun’s lower angle and the signal coming from about 350 to 400 miles to the north.

I’ve heard KFI faintly along I-80 between Vallejo and Fairfield in the mid afternoon. From that vantage the signal may have gotten a boost due to the soil in the western Central Valley. On paper, it was well beyond the .01 mv/m. contour.


As far as records go, I’m curious if you were on a raft in the middle of the Pacific Ocean exactly between Hawaii and San Francisco, what you could pick up.

Then there’s 540 CBK in the Saskatoon Provence in Canada. 50kw on arguably the most conductive soil on the continent.

 
Michael Rivers Kramer said:
I’ve heard KFBK here in the LA area in the late morning, but it was winter and I just chalked it up to late occurring skywave due to the sun’s lower angle and the signal coming from about 350 to 400 miles to the north.

I’ve heard KFI faintly along I-80 between Vallejo and Fairfield in the mid afternoon. From that vantage the signal may have gotten a boost due to the soil in the western Central Valley. On paper, it was well beyond the .01 mv/m. contour.


As far as records go, I’m curious if you were on a raft in the middle of the Pacific Ocean exactly between Hawaii and San Francisco, what you could pick up.

Then there’s 540 CBK in the Saskatoon Provence in Canada. 50kw on arguably the most conductive soil on the continent.

Click to expand...
Did you see that? The map read "Gulf of America"! :eek:
 
Michael Rivers Kramer said:
I’ve heard KFBK here in the LA area in the late morning, but it was winter and I just chalked it up to late occurring skywave due to the sun’s lower angle and the signal coming from about 350 to 400 miles to the north.

I’ve heard KFI faintly along I-80 between Vallejo and Fairfield in the mid afternoon. From that vantage the signal may have gotten a boost due to the soil in the western Central Valley. On paper, it was well beyond the .01 mv/m. contour.


As far as records go, I’m curious if you were on a raft in the middle of the Pacific Ocean exactly between Hawaii and San Francisco, what you could pick up.

Then there’s 540 CBK in the Saskatoon Provence in Canada. 50kw on arguably the most conductive soil on the continent.

Click to expand...

When i lived in SE WY, I could hear KNZR 1560 from about 3pm till 9/10am most days at some level in the winter

THere were rare times when KNX Was audible all day in the winter.. now mind you at 11-12-1pm it was barely a carrier above the noise.. but they were there
 
I can't remember what time of year each of these were, but I heard KOFI at about 2:30 in the afternoon one day when I was a freshman in high school. Another day I heard KEX around the same time. I want to say the KOFI catch was mid-January.
 
Michael Rivers Kramer said:
I’ve heard KFBK here in the LA area in the late morning, but it was winter and I just chalked it up to late occurring skywave due to the sun’s lower angle and the signal coming from about 350 to 400 miles to the north.

I’ve heard KFI faintly along I-80 between Vallejo and Fairfield in the mid afternoon. From that vantage the signal may have gotten a boost due to the soil in the western Central Valley. On paper, it was well beyond the .01 mv/m. contour.


As far as records go, I’m curious if you were on a raft in the middle of the Pacific Ocean exactly between Hawaii and San Francisco, what you could pick up.

Then there’s 540 CBK in the Saskatoon Provence in Canada. 50kw on arguably the most conductive soil on the continent.

Click to expand...
A couple of corrections. I meant to say .1 mv/m and Saskatchewan instead of the Saskatoon.

Since this is the Seattle board, I do want to point out that KIRO 710 is audible in Portland. Not that it's that far, but the conductivity there isn't the greatest.
 
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