While WBBM is still copyable here in SE Michigan during the day, their signal is noticeably weaker here after they began sharing with WSCR. I haven't noticed much of a change at night however, they blast in here like they always have. Also common to hear WCKB on the frequency in the late afternoon/early evening prior to signing off from my location.
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AM Frequency of the week: 780"
- Thread starter cyberdad
- Start date
WBBM increases from 35000 watts Daytime to 42000 watts Nighttime. It is a few miles further away, and at that distance, 225 miles plus or minus, a few miles makes a big difference. The groundwave curves begin a steep downward slope at those distances.
Why is it only 35kw day, then 42kw night?
When it moved, it had to adjust to new AM standards.
They had to keep their interfering contours of the new site within the interfering contours of the old site. The electrical height and efficeincy also increased from the WSCR site. The vertical radiation characteristic of the increased height also does tricky things. Maybe someday they might change the rules back so that just the 0.5 mV/m contours of WBBM 780 and WSGW 790, for instance, don't overlap, and an increase closer to 50 kW Daytime might be possible. Many of our posters here are familiar with that situation. They might be able to design a skirted radiator for WBBM which is shorter electrically at the WSCR site to be 50 kW again. rfry and some of the others here might be able to advise on the feasibility of that design.
KFI had to have a special sectionalized tower designed that was shorter after it was hit by an airplane in order to increase the efficiency and custom optimize the vertical radiation characteristic at each angle of departure to stations KFI interfered with, such as WOI and the former WWLS (KWPN) and the former WHKK (WHLO), so as not to increase their NIF. This was done to stay 50 kW, even at the same site.
KFI had to have a special sectionalized tower designed that was shorter after it was hit by an airplane in order to increase the efficiency and custom optimize the vertical radiation characteristic at each angle of departure to stations KFI interfered with, such as WOI and the former WWLS (KWPN) and the former WHKK (WHLO), so as not to increase their NIF. This was done to stay 50 kW, even at the same site.
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It appears that more than just protections with adjacent-channel WSGW might be involved in the lower TPOs of WBBM when using the WSCR tower.
Great circle path distance between WBBM and WSGW actually increased by about 4 miles after the WBBM move (old= 237 miles, new = 241 miles; bearing to WSGW = 63°). The nominal elevation angle of 19.8° for single hop skywaves from WBBM's old site to the WSGW site was reduced by 0.3 degrees after their move. That is not much of a consideration with respect to any difference in WBBM's new and old elevation patterns at/near that skip angle, but maybe it was enough (in theory).
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The application of WBBM reduced the overlap mutually between the 0.25 mV/m ground wave of each to the 0.5 mV/m ground wave of the other, it didn't eliminate it. To increase it would require a return to the old rule of 0.5 mV/m to 0.5 mV/m of each. I knew there were others, but I would have had to download the application.
Thanks, WahooWah.
My work colleague from LaGrane/Auburn was definitely one of the best co-workers of my 40+ year broadcast/print/online nedia career. I worked with him for about a dozen years on a leading global electronics industry trade publication. When he traveled with me, he brought value to every appointment I brought him to. Very knowledgeable and great fun to be around. Our clients loved him!
My work colleague from LaGrane/Auburn was definitely one of the best co-workers of my 40+ year broadcast/print/online nedia career. I worked with him for about a dozen years on a leading global electronics industry trade publication. When he traveled with me, he brought value to every appointment I brought him to. Very knowledgeable and great fun to be around. Our clients loved him!
WBBM 24/7, and never anything else, at my home which is just under 200 miles due west of their transmitter. However, it's not what I think I remember it used to be. I don't know if my memory is correct about this, or if it's that there is just more overall noise on the dial now. The volume on the daytime signal seems lower than it used to be. It's frustrating because I rely on it somewhat for 24/7 news (along with NPR), on an AM radio dial where there's less and less programming that interests me (a personal aside).
I used to once or twice a year drive the entire length of U.S. 30 across Iowa. Customers in Cedar Rapids and Ames, then on to a major Customer in Columbus, Nebraska. WBBM was listenable daytime on a good car radio, all the way to Ames. Around Carrol, Iowa, about 65 Miles west of Ames, WBBM would start mixing with WJAG from Norfolk, Nebraska. By the time I got to Dennison, Iowa, the next town west of Caroll, by about 30 miles, WJAG completely took over.
It would be interesting to repeat this drive as a good test of what the difference is between 35 and 50kw is in a region with lots of open area and very good ground conductivity.
Sidebar point: I discovered that doing my runs to Nebraska on (mostly) 2-lane U.S. 30 was pretty much the same amount of actual driving time as doing it on I-80....and much more relaxing.
......Calling on Mario.....Breaker breaker 1-9, I need a radio check on MarioMania
Mario, can you hear KKOH out of Reno? Supposedly, there 50KW signal is supposed to cover the bay area, but I can't hear them on any of my radios here in San Jose. I would expect at least a faint and weak signal, but all I hear is a heavy, loud static ( almost sounds like a waterfall )
Mario, can you hear KKOH out of Reno? Supposedly, there 50KW signal is supposed to cover the bay area, but I can't hear them on any of my radios here in San Jose. I would expect at least a faint and weak signal, but all I hear is a heavy, loud static ( almost sounds like a waterfall )
KKOH is not a Class I/Class A, and doesn't have a protected skywave. Not sure what other stations could be interfering, and of course, there's too much electrical noise at most locations.
The "waterfall" you describe sounds like digital IBOC sideband interference. Not sure what station that could be either.
Yep I can confirm that 770 KCBC is likely the source of your troubles, as it is close to San Jose, and runs IBOC.
Interesting. I've heard of IBOC, but didn't know what it was or what kind of interference it caused or what it sounded like.
The "waterfall" sound does move the RF meter on my RF-2200 to a 2 or 3, its like a dead signal with lots of heavy static. I also did not realize it, but the loud static sound is on both sides of 770 KCBC, but a tad louder on 780 than on 760/750. If there is a weak KKOH, its under that IBOC noise then.
Thanks for confirming what this noise was. It has been bugging me for some time. At night, when KFMB 760 out of San Diego fades out, that same noise/static is there.
Lastly, as the evening rolls on after 6pm, KKOH signal does begin to peak through and gets stronger as the night wears on.
The "waterfall" sound does move the RF meter on my RF-2200 to a 2 or 3, its like a dead signal with lots of heavy static. I also did not realize it, but the loud static sound is on both sides of 770 KCBC, but a tad louder on 780 than on 760/750. If there is a weak KKOH, its under that IBOC noise then.
Thanks for confirming what this noise was. It has been bugging me for some time. At night, when KFMB 760 out of San Diego fades out, that same noise/static is there.
Lastly, as the evening rolls on after 6pm, KKOH signal does begin to peak through and gets stronger as the night wears on.
Locally, KLZ's hash (despite being 95 miles away) destroys the neighboring frequencies, but with patience, the skywave signals will occasionally overtake the IBOC hash, which has allowed me to grab KRAI and WNAX at night.
Luckily, it doesn't happen here with KSL so I can still hear KTSB (I still want to call it KFAQ) at night, but I do agree that the IBOC self noise can be a hinderance to DX. I do like being able to see the call letters on screen though; I think maybe we should have invested our time into a form of AM RDS along with C-QUAM, possibly? Then the noise would go down while being more useful.
WBBM at night here in NJ, and it sounds like they're using old CRL Systems processing. It has that characteristic slightly nasally sound to it.
I have noticed this regarding the WBBM audio quality here in the Kansas City. Not the best sounding AM station.
Bob
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