What is your reception on 820 AM at night?

[rfry]

Interesting ... but based on transmit power and antenna pattern, still not quite close enough for what I was looking for. Although, if it was powerful and/or directional enough to still be CLEARLY audible (by general population standards) over 400 miles away at noon in summer, assuming an average ground conductivity under 1 mS/m and a transmit frequency over 1500 kHz, then that distance might be ok. At the weakest, though, it should completely overload a cheap receiver so that it wouldn't hear ANYTHING else, not even an FM station on that tower.

Unfortunately, what you are "looking for" is impossible in the real world.

Not even a Class A, 50 kW, 24/7 AM broadcast station on a low AM broadcast frequency could meet your criteria.

RF

 

[stormy01]

Back to WIND, I wonder what the effective radiated power of their day and night patterns are. That too would account for their great signal to the north.

The FCC database here: http://transition.fcc.gov/mb/audio/amq.html
A sample of some of the Chicago "powerhouses"
WIND 560 RMS Augmented: 681.40 mV/m at 1 kilometer (daytime) 688.97 mV/m at 1 kilometer (nighttime)
WSCR 670 RMS Augmented: 379.00 mV/m at 1 kilometer (daytime & nighttime)
WLS 890 RMS Theoretical: 394.29 mV/m at 1 kilometer
WMVP 1000 RMS Augmented: 2902.01 mV/m at 1 kilometer (daytime) & 2743.95 mV/m at 1 kilometer (nighttime)

There must be more to this than just comparing the mV/m of a signal at 1 kM. I would venture to guess that for directional stations, that maximum signal is in the largest lobe. Also, IF things were equal (which they're not: equal power of stations, 1/4 wave towers (some are some 1/2 wave [or slightly more, 190°], differing ground conductivities, etc.) The physics of higher frequencies on the "standard broadcast band" (AM, 530-1700 kHz) are that stations on higher frequencies are attenuated more for a given distance as one gets further away from the transmitter site.

There are too many variables in the real world, and that's why a lot people say WLS's signal is a shadow of it's former self because of the degraded ground conductivity in the area over the years surrounding its transmitter site, while people are amazed that WIND often "sounds" close to a 50 kW station, though they are only 5 kW TPO and many of us know they are near water. It's probably seems like comparing apples to oranges, a directional to an omnidirectional station, though I'm sure there are formulas to compare the two. It's been said that WWL 870 in New Orleans is about 400kW ERP, and WMVP 1000 Chicago is about 200 kW ERP, but I have not found any formulas for this!

Perhaps Mr. Fry can kindly help us out with this? Thanks!

 

[Schroedingers Cat]

For Nondirectional Theoretical fields, you have to multiply by the square root of the power. For WIND, you have to look at the maximum inverse directional fields and IDF in particular directions in the DA information section (AM Query).

To compare Class As and Class Bs, it is more logical to use the minimum Class B efficiency, 282 mV/m @ 1 km for 1 kW as a reference. Many Class Bs are shoehorned in at minimum efficiency with short towers, or even in some cases, they are still licensed with a reduced input power. Formerly, many of these stations burned off power in series limiting resistors. When the "energy crisis" rolled around circa 1974, the folly of wasting power in this way was exposed, and they just reduced power input and took out the SLRs. They continued to be licensed at the nominal power levels {250,500,1000,2500,5000,10000,25000,50000}.

To use this reference take the inverse nondirectional or directional field, divide by 282, and square the result, to come up with an "ERP". Some advocate 300 mV/m @ 1 km or 310 mV/m as a reference. The only place I have seen this "codified" was for 300 mV/m in treaties. But many omni Class Bs would end up with an "ERP" below the licensed power if 300 mV/m is used as a reference.

 

[Schroedingers Cat]

Example: For 50 kW WLS, inverse field is,

394.29 * SQRT(50) = 2788.05 mV/m @ 1 km (1732.38 mV/m @ 1 mile)

Compared to a 50 kW Class B at minimum efficiency, this is the equivalent of about 98 kW.

 

[pianoplayer88key]

Interesting ... but based on transmit power and antenna pattern, still not quite close enough for what I was looking for. Although, if it was powerful and/or directional enough to still be CLEARLY audible (by general population standards) over 400 miles away at noon in summer, assuming an average ground conductivity under 1 mS/m and a transmit frequency over 1500 kHz, then that distance might be ok. At the weakest, though, it should completely overload a cheap receiver so that it wouldn't hear ANYTHING else, not even an FM station on that tower.

Unfortunately, what you are "looking for" is impossible in the real world.

Not even a Class A, 50 kW, 24/7 AM broadcast station on a low AM broadcast frequency could meet your criteria.

RF

Well ok then... just curious - how close could someone come with an end-fire array consisting of, say, 20 vertical antennas (bi-segmented, insulated & fed at the center, each one having an efficiency of at least 510 mV/m @ 1 km @ 1 kW), phased as an end-fire array (90° spacing & phasing, IIRC from looking at a few websites a few minutes ago), with each tower having its own dedicated 2 megawatt transmitter (obviously something you wouldn't be doing on U.S. soil), transmitting on either 540 kHz or 153 kHz, and assuming an all-saltwater path? Is there a chance that, for example, at about 824 km in the direction of the main lobe, it may still have enough oomph to be indicating about "96 to 98 dBµ" on your Tecsun PL-310 using only its built-in ferrite antenna?

Or, maybe for something a little less far out in space... Is it possible that some people (who don't work for the station in question) may live close enough to it so that if, for example, they had a Tecsun PL-310, it would be indicating "98 dBµ" on all harmonics up to the 21.95 MHz end of its shortwave coverage, and might even register upwards of 40-60 dBµ in harmonics in the FM band (assuming they're using only the built-in ferrite), or, would be about as "strong" of a signal, using only the built-in ferrite, as you might normally get about 0.05 km from a class A 50kW (for example WHO, KSTP during daytime operation or KFBK in their maximum lobe [and in case you may not have figured it out I guess I could admit I've taken a liking to the efficiency of stations using segmented antennas that are the size, relative to the wavelength, that KSTP and KFBK use ]), using the PL-310 plus a beverage, 12+-foot air-core loop and 18-inch ferrite sleeve loop antenna, each one independently tuned and oriented for maximum gain of the station?


As for ERP, I've sometimes wondered what it was supposed to be calculated relative to. For directional arrays, I usually have been calculating based on their transmit power, RMS @ 1 km, and specified field @ 1 km in my direction. For example, 1170-KCBQ transmits with 50 kW about 15 km from me at a heading of 7.21° (reverse 187.22°). Their RMS Augmented field is 2628.2 mV/m @ 1 km, and their field in my direction seems about 3935 mV/m @ 1 km. Applying the equation "50*(3935/2628.2)^2" reveals that they have an ERP of about 112 kW toward me.

 

[Signal]

It's WBAP all the time here at night.

 

[FreddyE1977]

When I get anything it is generally CHAM out of Hamilton, ON.
I think I may have gotten WBAP once or twice.

 

[nsa1]

Usually WOSU & WBAP mix, if the channel is not obliterated by WGY's IBOC. Rarely CHAM is in the mix. Late winter nights WBAP is often clear with little or no interference.

Near Cleveland OH.

 

[KTN Corp]

Interference in Houston.  Something is messing with WBAP when I was DXing in the car tonight.  It might be HD hash or a Mexican station(?).

 

[FreddyE1977]

When I get anything it is generally CHAM out of Hamilton, ON.
I think I may have gotten WBAP once or twice.

Guess I should have qualified that. Every so often WOSU seems like they are just a bit
tardy in powering down. When that happens I will get them fairly well until they do.

 

[Buckeyes2001]

I get a double dose of IBOC on this channel, from WGY 810 and WCCO 830. Underneath all that hash is usually WVSG/Columbus, OH and WBAP/Dallas, TX mixed.

 

[radioman148]

In the near north Chicago suburbs it used to be an easy WBAP every night. However, ever since WCPT went on at night it's messy mix of the two at my location.

 

[cyberdad]

In the near north Chicago suburbs it used to be an easy WBAP every night. However, ever since WCPT went on at night it's messy mix of the two at my location.

For me, 25-30 miles west of you, it depends on which one I decide to null. Both are usually about equal.

 

[audioguy]

In the near north Chicago suburbs it used to be an easy WBAP every night. However, ever since WCPT went on at night it's messy mix of the two at my location.

So upset about this! They took a perfectly usable skywave signal and made a total useless pile of crud out of it by authorizing this garbage station (WCPT) to stay on the air at night. I keep trying to console myself by the fact that WBAP doesn't broadcast anything unique or interesting, it's the same syndicated crud you can get on 1,000 other stations. Not like it used to be!

 

[radioman148]

In the near north Chicago suburbs it used to be an easy WBAP every night. However, ever since WCPT went on at night it's messy mix of the two at my location.

So upset about this! They took a perfectly usable skywave signal and made a total useless pile of crud out of it by authorizing this garbage station (WCPT) to stay on the air at night. I keep trying to console myself by the fact that WBAP doesn't broadcast anything unique or interesting, it's the same syndicated crud you can get on 1,000 other stations. Not like it used to be!

Totally agree and I can't null WCPT because they are both in the same direction from my location.

 

[cyberdad]

Put Bill Mack back on the WBAP overnight show, and I'll be upset about WCPT being on myself! ;D

 

[Darth_vader]

Same as it is during the daytime; just a slightly raspy-sounding image of KPAM (860) due to my proximity to the transmitter site.

 

[schmave]

Here in Thornville, Ohio, it's a mix of WVSG and WBAP, and neither of them is really listenable because of the other. WBAP does sound good in western and southwest Ohio at night because of WVSG's null. I remember hearing WBAP loudly one morning in a hotel in downtown Cincinnati several years ago, an hour or so before sunrise.

 

[vo1001swl]

Heard here in Newfoundland on 820 the most often is Radio Paradise from Nevis-St. Kitts in the Caribbean. Others from time to time include CHAM, WNYC, & WBAP

 

[radioman148]

Heard here in Newfoundland on 820 the most often is Radio Paradise from Nevis-St. Kitts in the Caribbean. Others from time to time include CHAM, WNYC, & WBAP

Wow--WBAP in Newfoundland is a helluva catch!