Engineering question

[sptdfb]

Greetings. Re the lease agreement that Jesse Dunn apparently has struck with Lieberman to move the KCOH programming to 1230 AM, I'm trying to help a colleague explain the difference in strength between a 1,000-watt station and a 5,000-watt station. Is it five times stronger, or are there orders of magnitude involved as in earthquake measurements? And, since I don't know the transmitter locations for either station, are there factors there as well that limit (or not) the listening area for 1230 AM, particularly when compared to 1430 AM? Thanks.

David Barron

 

[johndavis]

Greetings. Re the lease agreement that Jesse Dunn apparently has struck with Lieberman to move the KCOH programming to 1230 AM, I'm trying to help a colleague explain the difference in strength between a 1,000-watt station and a 5,000-watt station. Is it five times stronger, or are there orders of magnitude involved as in earthquake measurements? And, since I don't know the transmitter locations for either station, are there factors there as well that limit (or not) the listening area for 1230 AM, particularly when compared to 1430 AM? Thanks.

David Barron

Hi David,

It's not that simple with AM stations.

1. Frequency matters. 5000 watts at the low end of the dial (540) will cover more ground than 5000 watts at 1230 and 1430. But generally speaking, 5000 watts will cover more ground than 1000 watts.

2. Distance matters. Based on the class of station, some frequencies have stations closer together than others. At night, that means they will step on each other, as AM signals will bounce off the ionosphere at night and travel farther. 1230 is pretty much a garbage signal in any city because they're spaced close together. (That nighttime propagation doesn't help you when your neighbor is stepping on you.) I worked for one in Arizona that had a non-directional pattern and it was a big circle during the day, but at night our map looked like a pair of lips because interference from everyone nearby on 1230 wiped out half of the listening area. If you listened when we would turn off our transmitter for maintenance at night it was like listening to a loud murmur of all the other nearby 1230s on top of us.

KQUE tried an experimental night time synchronized booster that appears to still be licensed, but I'm not sure if they still use it because I was told it caused more interference than it solved. http://licensing.fcc.gov/cgi-bin/prod/cdbs/forms/prod/getimportletter_exh.cgi?import_letter_id=900

Here's a list of all the stations in Texas on 1230. It's noisy. http://transition.fcc.gov/fcc-bin/a...&slat2=&NS=N&dlon2=&mlon2=&slon2=&EW=W&size=9

3. Directional matters. Some stations have a single tower and broadcast in a non-directional pattern. Others have multiple towers to aim the signal away from nearby stations on neighboring frequencies. If the signal is pointed away from you, you could be looking at the towers and not hear it.

Here's FCC records for both stations. KCOH is 5000 watts daytime and 1000 watts at night in a directional pattern.
http://transition.fcc.gov/fcc-bin/a...&slat2=&NS=N&dlon2=&mlon2=&slon2=&EW=W&size=9

Here's a somewhat crude map of the day pattern: http://radio-locator.com/cgi-bin/pat?call=KCOH&service=AM&status=L&hours=D Night: http://radio-locator.com/cgi-bin/pat?call=KCOH&service=AM&status=L&hours=N


Here's KQUE. 1000 watts day/night
http://transition.fcc.gov/fcc-bin/amq?call=KQUE

Crude coverage map: http://radio-locator.com/cgi-bin/pat?call=KQUE&service=AM&status=L&hours=U

My analysis, which is worth about what you paid for it: KCOH is a better facility than KQUE, but the city has expanded well beyond both of their patterns. Within the loop, it's probably a wash.

 

[Mediafrog+]

The KQUE 1230 coverage is horrible, but it does provide a decent signal over inner-city neighborhoods that are heavily African-American. These areas probably contain a lot of older (55+) listeners who have continued to listen to KCOH out of sheer habit.

The 1430 daytime signal is better. Both stations' nighttime coverage is awful, being pretty much unlistenable more than 12-15 miles from downtown.

Wonder if the KCOH call will move to 1230? That would mean an end to the long history of the KQUE call in Houston, and something new for 1430.

 

[foursider]

Generally speaking, on AM, when you quadruple the power; you only increase the coverage by about 25%. Of course, this depends on which end of the dial you are on and the ground conductivity in the coverage area. I once engineered a 250 watt daytimer that increased power to 1000 watts. We got about 25% more coverage. Not much bang for the investment involved; but, the 250 watt directional proof showed that we could increase to 1000 watts due to the poor ground conductivity in that part of the state.

 

[johndavis]

The KQUE 1230 coverage is horrible, but it does provide a decent signal over inner-city neighborhoods that are heavily African-American. These areas probably contain a lot of older (55+) listeners who have continued to listen to KCOH out of sheer habit.

The 1430 daytime signal is better. Both stations' nighttime coverage is awful, being pretty much unlistenable more than 12-15 miles from downtown.

Wonder if the KCOH call will move to 1230? That would mean an end to the long history of the KQUE call in Houston, and something new for 1430.

Surprisingly enough, 1430 comes in great out in Sienna Plantation at night. The directional array must be pointed straight at us. While that's Missouri City, I doubt that's where KCOH's audience lives. I haven't seen hot zips, but my gut feeling is that 1230's pattern is enough to serve their current hot zips after sunset. When they open the mic on KCOH, they're talking to the city and not the suburbs. (I'm the anomaly: the white guy who likes the mix of 1980's-1990's R&B that KCOH plays at night that you won't find on KMJQ anymore.)

News reports suggest that the KCOH calls will move to 1230 when the LMA begins. I wouldn't be surprised if Lieberman moves the KQUE calls to some other property. There's a lot you can do with QUE when you're programming en espanol.

 

[rbrucecarter5]

I just hope the new format on 1230 doesn't slop over onto 1220 - which is one of the few stations on AM which is programming oldies / standards, and is a bright spot on the otherwise horrible AM band in Houston. I don't care it is weak and from Madisonville, it is really good.

 

[rageradio]

The format won't have any effect whatsoever on the signal and any neighboring channel unless Lieberman starts tinkering with the transmitter

 

[fadedglory]

Trying to guess when KQUE went to 1kw nights from 410 watts; also remembering posts from years ago stating that the ground plates facing westerly had been damaged due to corrosion due to the storage of used batteries adjacent to the aerials. Has going to to 1kw help overcome the loss of coverage due to the damage, or is it still the same as before?

 

[bradgoehl]

The whole ground system there could use replacement, but due to environmental considerations its unlikely.
You are correct on the batteries though, the site was once a dumping ground for old battery casings. Hence the prohibition on digging and lack of ground system replacement.

 

[johndavis]

Trying to guess when KQUE went to 1kw nights from 410 watts; also remembering posts from years ago stating that the ground plates facing westerly had been damaged due to corrosion due to the storage of used batteries adjacent to the aerials. Has going to to 1kw help overcome the loss of coverage due to the damage, or is it still the same as before?

Stations on 1230 used to be 1000 day/250 night. In the late 80's, the FCC changed the rules on "Local" class C frequencies and allowed them to run 1000 day/night as long as they accepted whatever interference came from other stations on the same frequency increasing from 250 to 1000. Based on the files on the FCC website, they stopped reducing power in 1988.

The 410 watt transmitter was an experimental on-channel booster off West Little York to run at night that was licensed in 1987. The FCC website says it's still licensed. I'm not sure if it's really still in use because it supposedly caused more problems than it solved when it went in.

 

[fadedglory]

Thanks! Was wondering how it went from 250 to 410 watts nights for a time there as I recall the interference while listening after sunset when it was "new 1230 am fun radio", hard to believe that was almost 25 years ago.

 

[fadedglory]

Thanks! Was wondering how it went from 250 to 410 watts nights for a time there as I recall the interference while listening after sunset when it was "new 1230 am fun radio", hard to believe that was almost 25 years ago. The carrier would be buried underneath the noise from the current every 15 seconds or so especially while travelling on the West Loop at the time.

 

[johndavis]

Thanks! Was wondering how it went from 250 to 410 watts nights for a time there as I recall the interference while listening after sunset when it was "new 1230 am fun radio", hard to believe that was almost 25 years ago. The carrier would be buried underneath the noise from the current every 15 seconds or so especially while travelling on the West Loop at the time.

...and that's exactly why synchronous boosters don't work on AM. They only work on FM in places where terrain keeps the two signals separated. With AM there's no real way to keep them from stepping on each other, so they end up nulling each other out as you drive. But I suppose somebody had to try it to see if it would work.

 

[rageradio]

..on that note. I can remember listening to 790 in the mornings on the way to school (early/mid 80s). Every single day at the same exact spot off of Mykawa & Airport, it would quickly fizzle out. I wondered if it was some sort of "hand off" to another transmitter or something, because the audio afterward was not as clean as before. Like my radio was going from one signal to another. Is that what that was? A synchronous booster?

 

[johndavis]

..on that note. I can remember listening to 790 in the mornings on the way to school (early/mid 80s). Every single day at the same exact spot off of Mykawa & Airport, it would quickly fizzle out. I wondered if it was some sort of "hand off" to another transmitter or something, because the audio afterward was not as clean as before. Like my radio was going from one signal to another. Is that what that was? A synchronous booster?

No, but 790 does change patterns at sunrise and sunset, so when that happens you'll hear the carrier drop for a couple of seconds as it changes from one array to the other. They use 4 towers during the day and 8 at night. The night pattern is narrower than the day; both are directional and put a lot of signal out over the bay.

Your for entertainment purposes maps... day: http://radio-locator.com/cgi-bin/pat?call=KBME&service=AM&status=L&hours=D
night: http://radio-locator.com/cgi-bin/pat?call=KBME&service=AM&status=L&hours=N

 

[rbrucecarter5]

..on that note. I can remember listening to 790 in the mornings on the way to school (early/mid 80s). Every single day at the same exact spot off of Mykawa & Airport, it would quickly fizzle out. I wondered if it was some sort of "hand off" to another transmitter or something, because the audio afterward was not as clean as before. Like my radio was going from one signal to another. Is that what that was? A synchronous booster?

No, but 790 does change patterns at sunrise and sunset, so when that happens you'll hear the carrier drop for a couple of seconds as it changes from one array to the other. They use 4 towers during the day and 8 at night. The night pattern is narrower than the day; both are directional and put a lot of signal out over the bay.

Your for entertainment purposes maps... day: http://radio-locator.com/cgi-bin/pat?call=KBME&service=AM&status=L&hours=D
night: http://radio-locator.com/cgi-bin/pat?call=KBME&service=AM&status=L&hours=N

I would have thought they would put more of a daytime null towards Lubbock - KFYO is a bit of a regional monster and makes it into the Western parts of the DFW area.

 

[rbrucecarter5]

The format won't have any effect whatsoever on the signal and any neighboring channel unless Lieberman starts tinkering with the transmitter

I don't know - KEYH 850 slops their garbage all over KONO 860. I wish KEYH would fix their audio chain and roll it off so Houston oldies listeners could have a decent shot at KONO. I've got radios with very good selectivity and can't eliminate that KEYH garbage.

 

[purpledevil]

The format won't have any effect whatsoever on the signal and any neighboring channel unless Lieberman starts tinkering with the transmitter

I don't know - KEYH 850 slops their garbage all over KONO 860. I wish KEYH would fix their audio chain and roll it off so Houston oldies listeners could have a decent shot at KONO. I've got radios with very good selectivity and can't eliminate that KEYH garbage.

Man, bruce, you are relentless. I don't care for the programming of KEYH either, but it's not garbage and you don't really have to repost that tidbit every other day.

On the other point you bring up, believe it or not I've logged KFYO from Bellville before. That thing is somewhat of a monster at 5,000 watts, but that has a lot to do with its dial position too and the fact that KBME doesn't exactly favor the NW areas of SE Texas.

 

[ChuckTiller]

KFYO is in Lubbock.

 

[purpledevil]

KFYO is in Lubbock.

I think you misinterpreted what I said, Chuck. I was able to pick up and log the Lubbock signal from my home in Bellville before, which to me was somewhat of a feat considering the distance from Bellville that KFYO is. The way I wrote it before does read a bit strange. Not sure why my sentence structure was off last eve.