Do you have reception problems due to drought?

[rtc]

Many parts of the country are in drought conditions
now.
Parts of the Southeast are in a prolonged severe
drought with no end in sight.
Has anyone had AM reception trouble with weaker
than normal stations being observed?
(This would be groundwave-soil conductivity issues.)
Around here some AM/MW test stations are weaker
than normal.
Of two longwave test beacons,one is markedly
weaker and the other can't be heard at all.

 

[Ai4i]

I have no personal experience with which to address your question,
but I find it interesting that the R-L maps show no appreciable effect from Lake Michigan on the four dominant clears in Chicago.
In some directions, the stations are stronger over the lake, but in others they are stronger over land.
It is as if the ground conductivity of the land under the fresh water is the variable, but this is a hard pill for me to swallow.

 

[davideduardo]

I have no personal experience with which to address your question,
but I find it interesting that the R-L maps show no appreciable effect from Lake Michigan on the four dominant clears in Chicago.
In some directions, the stations are stronger over the lake, but in others they are stronger over land.
It is as if the ground conductivity of the land under the fresh water is the variable, but this is a hard pill for me to swallow.

The individual Great Lakes have different conductivity per the FCC's rather shotgun approach conductivity tables. The apparent reason is that the mineral content of each lake is slightly different.

If you look at the table on http://hamwaves.com/ground/en/ you can see that the conductivity of salt water is 5,000 micromhos while fresh water is 1. (the chart is in SI, not the commonly used measure employed in the US for conductivity).

Freshwater conductivity also varies by temperature, but in general is about the same conductivity as dry, sandy soil. Think of it being about the same as Long Island, or, in tune with this weekend's concert, the Coachella Valley.

 

[Schroedingers Cat]

The skin effect would limit the effect of the soil underneath the water. My readings of E and M texts suggest that the skin depth would be larger for less effective conductors. The only differences I see is that Canada uses 10 and the US 8 for the Great Lakes. Environmental studies show larger conductivities near the shorelines due to ionic salts flowing into the Lakes.

 

[MarioMania]

The individual Great Lakes have different conductivity per the FCC's rather shotgun approach conductivity tables. The apparent reason is that the mineral content of each lake is slightly different.

If you look at the table on http://hamwaves.com/ground/en/ you can see that the conductivity of salt water is 5,000 micromhos while fresh water is 1. (the chart is in SI, not the commonly used measure employed in the US for conductivity).

Freshwater conductivity also varies by temperature, but in general is about the same conductivity as dry, sandy soil. Think of it being about the same as Long Island, or, in tune with this weekend's concert, the Coachella Valley.

My head's going explode trying to get what you just wrote David

Can you dumb it down for people who's not in the Radio Business

Now, Back on Subject, I don't know..It been dry in CA for 6 years, So I can't tell

 

[davideduardo]

My head's going explode trying to get what you just wrote David

Can you dumb it down for people who's not in the Radio Business

While salt water conducts radio signals about 150 times as well as the best soil, fresh water on average conducts AM signals about as poorly as the worst soil in the US.

 

[davideduardo]

The skin effect would limit the effect of the soil underneath the water. My readings of E and M texts suggest that the skin depth would be larger for less effective conductors. The only differences I see is that Canada uses 10 and the US 8 for the Great Lakes. Environmental studies show larger conductivities near the shorelines due to ionic salts flowing into the Lakes.

In the case of either nation, they are apparently showing that the great lakes have enough salts and dissolved conductive materials to raise the conductivity from that of "pure" fresh water with no mineral content... such as distilled water. Or, perhaps I should express that as a question to you?

 

[Schroedingers Cat]

I saw that chart showing 1 for smaller rain and spring fed lakes. I would say you are right about the Great Lakes being higher due to ionic salts. Mineral ores are usually not as ionic. I saw a Lake Erie near shoreline study showing areas of 20-40 if you convert the units they used (power of ten difference, but forget exactly) to mS/m. They did find small freshwater lakes near the 1 mS/m level.

 

[Ai4i]

DE, could you please explain why KSL does not show a huge spike to the north northwest?
That lake is several times saltier than any of the oceans.

 

[davideduardo]

DE, could you please explain why KSL does not show a huge spike to the north northwest?
That lake is several times saltier than any of the oceans.

Two possibilities.

1, The lake is not big enough to make much of a difference, or,

2. The propagation maps do not show the Great Salt Lake as having different characteristics.

I looked the Lake up, and its size varies from about 900 square miles to nearly 3.300 square miles according to area rainfall. Its maximum depth when "full" is about 40 feet.

Lake Michigan is 22,000 square miles and has a maximum depth of over 1,000 feet. I'd guess that with the waxing and waning in size of the GSL, and shallow depth, it is hard to include it accurately in conductivity tables.

When I saw KSL many years ago, its site was very near the lake's edge. I wonder how far from the water it is today?

 

[Ai4i]

I would like to go to the north edge of the lake and test whether their signal is really just 2mv/m.
By the map, they do betterly in the opposite direction toward Provo.
They appear to be about 2½ to 3 miles in the dry.

 

[rbrucecarter5]

Completely pure, distilled water is an insulator. If PH is either high or low, it is a conductor. Most fresh water lakes, purified naturally by plants, etc. are pretty close to pure. But when waste is added, it becomes more and more conductive. I've measured my pool, with about 1/10 the salt content of the ocean, at 5000 Ohms/meter. Not the units they use for ground conductivity measurement. Those ground conductivity maps you see everywhere come from the International Geographical Year almost 6 decades ago. I can't help but think it is time for somebody to improve them. That little patch of 30 under Lubbock leads to some fantastic AM reception!

 

[rbrucecarter5]

There is no drought here in Houston, we are almost 20 inches over the annual average - DX conditions, however, are still bad.

 

[schmave]

I've absolutely noticed it here in central Ohio. WLW and WTAM, among other regional stations, were weaker this summer than I can remember in quite some time.
As some of you know, I do not have the best car radio when it comes to AM signals. One of the very few upsides is it's easy to tell when a station is stronger or weaker. WLW usually has a very good signal here in Columbus, and it could be considered strong in the suburbs closest to Cincinnati. Now that it has cooled down the past few weeks and it's rained a decent amount, the signal is back to what it should be. WTAM is much weaker than WLW in any case, but it also is back to normal level around here.

 

[davideduardo]

There is no drought here in Houston, we are almost 20 inches over the annual average - DX conditions, however, are still bad.

If DX conditions are bad, consider issues specific to your location, starting with man-made interference levels.

For AM (medium wave) DX, we are well into the low part of the sunspot cycle so DX is improving on a global level. On FM, we are out of the skip opportunities that summer provides, so the next six months are the least DXable of the year.

 

[rbrucecarter5]

If DX conditions are bad, consider issues specific to your location, starting with man-made interference levels.

For AM (medium wave) DX, we are well into the low part of the sunspot cycle so DX is improving on a global level. On FM, we are out of the skip opportunities that summer provides, so the next six months are the least DXable of the year.

You must know that I would exhaust all simple things like interference first. I have relentlessly purged my home of all sources of interference, leaving a clean RF environment. The worst issue comes with government mandated switching wall warts that supposedly offer a greener power alternative. Every single one of them has been based on a Chinese design that has a crucial defect. They use an 0402 resistor where they need to dissipate 1 Watt, meaning that it should be a 2512 case - minimum. When the resistor blows - what was a quiet wall wart all of the sudden puts out tremendous interference levels. I think it is a snubber resistor. The supply still puts out the right DC level, but ripple goes from millivolts to volts. It cannot be good for the equipment it is powering, but it works, so nobody cares. I have gone into half a dozen of them powering various things in my house, different units being powered. Same story every time - a little black spot where the resistor has burned through. I wire in the right wattage resistor, interference is gone immediately. There must be millions of them out there. Tens of millions. So the AM band takes another hit because some engineer in China can't properly design a switching power supply. Mandated by law - everybody has to have one. The old linear wall warts are too wasteful.

As for FM, the rules are a bit different here. When a sea breeze sets up afternoon thunderstorms - after they clear out the FM DX is amazing no matter what time of year. It doesn't set up every day like it did in Florida, but it is often enough to be predictable no matter what time of year. I just don't stay up for it like I used to - not even DX targets have any sort of compelling programming. I still have fun in Florida - I have set up family members there with tuners and antennas so they can get semi-reliable late night reception of Miami and Tampa stations from East Central Florida. Car reception is amazing late at night. Just about any station on the peninsula is there. Enough stations even I can find something to listen to. 80, 90 frequencies with stations.

 

[Ai4i]

I have set up family members there with tuners and antennas so they can get semi-reliable late night reception of Miami and Tampa stations from East Central Florida.

When I lived in Gainesville FL in the early-middle 1970's, I could hear four stations on each of 100.7 & 101.5. One pair was in Miami, and others were in Tampa, Brunswick, and somewhere to the northwest. This was a looong time ago.

 

[ftballfan]

When I lived in Gainesville FL in the early-middle 1970's, I could hear four stations on each of 100.7 & 101.5. One pair was in Miami, and others were in Tampa, Brunswick, and somewhere to the northwest. This was a looong time ago.

When I was in Orlando back in March, 94.5 and 95.3 from Fort Myers overrode the locals at times. Several Miamis were in, along with almost everything from Tampa and Fort Myers.

And speaking of 100.7 and 101.5, would the fourth pair have been Mobile/Pensacola?

 

[Ai4i]

And speaking of 100.7 and 101.5, would the fourth pair have been Mobile/Pensacola?

Or Tallahassee or Georgia or Alabama.
I said "somewhere to the northwest" because that was a long time ago and stations have changed call letters and frequencies and moved geographically.
I seem to recall that one of them was R&B and monaural, likely simulcastang an AM station, but maybe not.

 

[tomservo]

Or Tallahassee or Georgia or Alabama.
I said "somewhere to the northwest" because that was a long time ago and stations have changed call letters and frequencies and moved geographically.
I seem to recall that one of them was R&B and monaural, likely simulcastang an AM station, but maybe not.

Both Tallahassee and Pensacola have stations on 100.7 & 101.5... Tallahassee's are C2/C3 while Pensacola's are both full C with big coverage areas.

Summer DX here was a letdown this year on the Alabama Gulf coast. I never heard anything further away than New Orleans. In years past, Jackson, Montgomery, Baton Rouge and Tallahassee were not uncommon at night.

Going back to the OP, we're not in much of a drought so I can't tell if reception is any worse. I would love to know if drier ground affects AM reception noticeably.