Why Is 1640 KDIA Running 10,000 Watts at All Times?

[Gregg.]

Nearly all AM stations in the expanded band, 1610 to 1700 kHz, run the same power. 10,000 watts by day, 1,000 watts at night, using a non-directional antenna.

I know XEPE Tijuana was an exception because it is licensed to Mexico, not the U.S. It runs 10,000 watts around the clock. It had been the English language ESPN sports station for San Diego until late last year when its operator ran into financial problems.

But now I see 1640 KDIA Vallejo CA, serving the San Francisco market, is also running 10,000 watts around the clock. I wonder why it is an exception to the rule for all U.S.-based stations in the expanded AM band?

 

[SomeRadioGuy]

Nearly all AM stations in the expanded band, 1610 to 1700 kHz, run the same power. 10,000 watts by day, 1,000 watts at night, using a non-directional antenna.

I know XEPE Tijuana was an exception because it is licensed to Mexico, not the U.S. It runs 10,000 watts around the clock. It had been the English language ESPN sports station for San Diego until late last year when its operator ran into financial problems.

But now I see 1640 KDIA Vallejo CA, serving the San Francisco market, is also running 10,000 watts around the clock. I wonder why it is an exception to the rule for all U.S.-based stations in the expanded AM band?

Thats because its directional at night.

1670 KHPY near LA runs liek 9kw at night, its directional

WWRU near NYC runs 10kw at night, its directional.

The original intention was 1kw night non directional

 

[fybush]

There are several such exceptions in coastal areas, all using directional antennas to maintain the equivalent of 1 kW toward other co-channel stations inland.

 

[alok]

KDIA does run 10 kw night using a directional antenna ,plus they do something that is alittle unusual for an expanded band station ,they operate day non-directional from KKSF's 910 towers ,near Richmond,CA at 10 kw NON-DA day.
This daytime location gives them a great signal over the entire area, SF and San Jose ,including Vallejo.
At night to cover their city of license which is Vallejo with a good signal and to keep covering SF good they operate from 4 towers at 10 kw ,pushing most of the signal west. The 4 tower array is just west of Vallejo. They loose some coverage in San Jose at night.
The two sites are no where near each other. The daytime site is off the SF Bay overlooking SF in Richmond,CA at Point Isabel the night time site is up near Hwy. 37 and the northside of SF Bay.

Al

 

[Schroedingers Cat]

The 10 kW DA Night must also not exceed the 1 kW nondirectional equivalent toward Canada. Not sure about Mexico. Maybe David knows more about the Agreement with Mexico. That's why you don't see any 10 kW Night Expanded Band stations in the Northern tier of States, where most AMs direct their signals toward Canada at Night. Toronto appears to be the X Band capital, with stations on 1610 (no AM BC stations in the US, just TIS), 1650, and 1690. CHHA 1610 directs its 6250 watts toward the US, and has a quasi Class A signal, better than CBE(F) 1550 and CKDO 1580 into the US, except very near TIS stations on 1610.

 

[Schroedingers Cat]

Looks like the entire arc of the DA pattern toward the Canadian Border is below 306 mV/m @ 1 km @ 1 kW (1/4 wave efficiency) Standard Pattern IDF. And the pattern has its major lobe in the general direction of Mexico, so apparently, the Agreement with Mexico allows it. But then again, there are almost no AMs left in Mexico.

https://www.fccdata.org/am_pattern.php?antid=103093

 

[davideduardo]

KDIA does run 10 kw night using a directional antenna ,plus they do something that is alittle unusual for an expanded band station ,they operate day non-directional from KKSF's 910 towers ,near Richmond,CA at 10 kw NON-DA day.
This daytime location gives them a great signal over the entire area, SF and San Jose ,including Vallejo.
At night to cover their city of license which is Vallejo with a good signal and to keep covering SF good they operate from 4 towers at 10 kw ,pushing most of the signal west. The 4 tower array is just west of Vallejo. They loose some coverage in San Jose at night.
The two sites are no where near each other. The daytime site is off the SF Bay overlooking SF in Richmond,CA at Point Isabel the night time site is up near Hwy. 37 and the northside of SF Bay.

Al

That is a bit optimistic. In metros, a 10 mV/m signal is where AM stations get about 95% of the fixed location listening (home or work). So that covers about 25% of the market. The 5 mV/m covers about 40%.

At night, due to the need to radiate the equivalent of 1 kw towards the continental US and Canada, the pattern is more narrow and the population covered is less.

The only advantage is being on a very clear and pretty much interference free frequency, but the high frequency and the metro noise level pretty much limit its coverage.

I'd rather have 500 watts at 550 than that one; it would cover more!

 

[Schroedingers Cat]

That is a bit optimistic. In metros, a 10 mV/m signal is where AM stations get about 95% of the fixed location listening (home or work). So that covers about 25% of the market. The 5 mV/m covers about 40%.

At night, due to the need to radiate the equivalent of 1 kw towards the continental US and Canada, the pattern is more narrow and the population covered is less.

The only advantage is being on a very clear and pretty much interference free frequency, but the high frequency and the metro noise level pretty much limit its coverage.

I'd rather have 500 watts at 550 than that one; it would cover more!

Are there any stations WAY-LOW on the dial still operating in Mexico? Looks like XEWW 690, but that is probably being used as a quasi US station. I would think that if there were any stations in Canada or Mexico operating on the X-Band, they would move to the low frequencies presently vacated. There are so many stations vying for frequencies in Toronto that 1610, 1650, or 1690 can't move down the dial. There has been some talk about a new station in the Toronto Area moving to 950, which was formerly used by CKBB Barrie, ON.

 

[SomeRadioGuy]

Are there any stations WAY-LOW on the dial still operating in Mexico? Looks like XEWW 690, but that is probably being used as a quasi US station. I would think that if there were any stations in Canada or Mexico operating on the X-Band, they would move to the low frequencies presently vacated. There are so many stations vying for frequencies in Toronto that 1610, 1650, or 1690 can't move down the dial. There has been some talk about a new station in the Toronto Area moving to 950, which was formerly used by CKBB Barrie, ON.

Yes.

XEPL 550 Ciudad Cuauhtémoc, Chihuahua, Mexico even runs some german programmign that ive heard in Wyoming
XEXSURF 540 Tijuana

 

[davideduardo]

Are there any stations WAY-LOW on the dial still operating in Mexico? Looks like XEWW 690, but that is probably being used as a quasi US station. I would think that if there were any stations in Canada or Mexico operating on the X-Band, they would move to the low frequencies presently vacated. There are so many stations vying for frequencies in Toronto that 1610, 1650, or 1690 can't move down the dial. There has been some talk about a new station in the Toronto Area moving to 950, which was formerly used by CKBB Barrie, ON.

Only one (IIRC) AM in Mexico City moved to FM as there were no conversion channels available. That means that 560, 590, 620, 660, 790 and 710 are all still going. Nearly the same in GDL, Puebla and Monterrey. Anything near or on the border on one of those low channels could not change due to protection of the USA. And some, like 540 in SLP had to continue as the AM gave "exclusive coverage" the FMs could not serve.

 

[alok]

I'd say KDIA does decent in SF at night because of the saltwater path , even with the night time transmitter site being further away from SF. That signal travels from the night time site to SF mostly all over saltwater.
San Jose is a different story with the signal traveling more over land from night time site ,there they might be more difficult to hear at night , at least heard decently.

Al

 

[Schroedingers Cat]

I'd say KDIA does decent in SF at night because of the saltwater path , even with the night time transmitter site being further away from SF. That signal travels from the night time site to SF mostly all over saltwater.
San Jose is a different story with the signal traveling more over land from night time site ,there they might be more difficult to hear at night , at least heard decently.

Al

I'd say your analysis is correct. But there is also a null fairly close to the direction of San Jose where the Night pattern is reduced from maximum. Apparently, there are some problems on fccdata.com site with the coordinates. It shows four towers at the Day site location in the water, and the same site at Night. Radio Locator seems to have the Night location corrected. Is it in a shallow marsh or actually in the water? Otherwise the coordinates may need correcting.

https://radio-locator.com/pats/KDIA_AM_LN.gif

https://www.fccdata.org/?facid=&cal...=&lmspl=&party_type=LICEN&latd=&lond=&lang=en

 

[Schroedingers Cat]

One more thing. I've seen conductivity maps of Europe which show the Gulf of Bothnia as 1000 mS/m, not 5000 mS/m, because it is somewhat isolated from the Atlantic Ocean. I wonder if the same could be true for San Francisco Bay and the Pacific Ocean. The man I call the Alt-FCC, Dave Doherty, because of his role in making FCC Data available even when the FCC doesn't, says that that he has observed huge diurnal tidal variations in conductivity in coastal areas, like near the mouth of the Hudson River. Obviously there has to be a lesser or greater gradual change in salinity as you approach the ocean. There can't be a conductivity cliff.

 

[fybush]

I'd say your analysis is correct. But there is also a null fairly close to the direction of San Jose where the Night pattern is reduced from maximum. Apparently, there are some problems on fccdata.com site with the coordinates. It shows four towers at the Day site location in the water, and the same site at Night. Radio Locator seems to have the Night location corrected. Is it in a shallow marsh or actually in the water? Otherwise the coordinates may need correcting.

https://radio-locator.com/pats/KDIA_AM_LN.gif

https://www.fccdata.org/?facid=&cal...=&lmspl=&party_type=LICEN&latd=&lond=&lang=en

Michi needs to tweak the way FCCData shows two-site AM stations - it maps the night towers at the day site by default.

The KDIA day site is one of the two KNEW 910 towers, which are indeed out in the water west of Albany. The night site is marshy land up near Sears Point, shared with KDYA 1190 Vallejo.

 

[SomeRadioGuy]

Michi needs to tweak the way FCCData shows two-site AM stations - it maps the night towers at the day site by default.

The KDIA day site is one of the two KNEW 910 towers, which are indeed out in the water west of Albany. The night site is marshy land up near Sears Point, shared with KDYA 1190 Vallejo.

and didnt fccdata.org use to show am station coverage patterns too? they dont anymore

 

[Schroedingers Cat]

I think they need to update those too. It seems like the FCC has a database of geographic coordinate points along the 2.0 mV/m and 0.5 mV/m contours based on M-3. It's probably made for use by the FCC engineering staff at least partly to process FM translators for AM stations. They probably update those irregularly. I think these databases can be used to plot contours on other types of maps, used in application software, and perhaps by fccdata.com and R-L type programs to create coverage maps for stations.