AM HD TURNOFF PACE ACCELERATES

If North American Philips / Magnavox started building radios in 1978, maybe a third of the AM stations would have stayed with a music format- even in 1990, many news/talk/full service AM stations still ran music programming on the weekends, and I listened to them in stereo AM: WTVN, WSPD, KMOX, WRMR, WCAU, WJR. etc

WLW ran a fair amount of music in those days as well, and not just country on "Truckin' Bozo" overnight. I remember a lot of music on the weekends on 700, ranging from oldies to then-current music. I don't remember much music on The Big One after about 1990.
As I remember, however, WLW never broadcast in stereo, at least as long as I have listened to them (I'm 38 now and heard a lot on WLW when I was in the car with my dad as a kid and growing up from there).

I remember the cover of Popular Electronics having a Magnavox AM stereo tuner about that time with a big adjustable ferrite bar antenna, and the test results from all the systems, including Belar. You are correct Dave that most stations didn't do their installs until the end of 82, early 83.

Ha! The Bone Fone! I actually bought one of those things from that same company. Completely useless.

DavidEduardo said:

Here is another Popular Electronics issue featuring AM stereo:

http://www.americanradiohistory.com/Archive-Poptronics/80s/1980/Poptronics-1980-08.pdf

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I still have my copy of that very magazine! Reminder of a bygone era that could have been. I still have my C-Quam AM radios. One of the legacies of the AM stereo era is the use of product detectors in the radio - required for C-Quam. Because product detection is superior to envelope detection - the C-Quam radios still sound great on mono AM! Enough reason to keep them around for the occasional music format still found on AM.

Back to the original thread topic.

At one point, St. Louis had four stations using HD on AM: KFUO (850), KMOX (1120), WSDZ (1260), and KATZ (1600). WSDZ and KATZ dropped their HD some time ago, and for a time, KFUO and KMOX dropped their HD signals as well.

Recently KFUO and KMOX have resumed broadcasting in HD.

I live in Plano, Texas and actually picked up the HD signal on KMOX last night. First time I've been able to do that.

tested said:

I live in Plano, Texas and actually picked up the HD signal on KMOX last night. First time I've been able to do that.

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Thanks for the tip on KMOX, tonight I got out my Sangean PDR 16 and tuned to 1120-KMOX and it seemed to come so close to locking in the HD; the HD logo kept flicking but it never locked in, same thing on 880-WCBS (which is usually drowned out by Cuba at my location) and also the HD logo was flickering on WBBM 880-Chicago, but didn’t seem close to locking in like 880 and 1120.

I have yet to hear AM HD, as luck would have it, the remaining HD AM station in this area (WDAE-620) turned off their HD shortly before I bought the SANGEAN 16. It is very sensitive on the FM and also very good for dx’ing on the AM band; although dx’ing here is only a winter time deal.

KRLD HD from Dallas is a not a rarity in Corpus Christi at night. Not as far as St Louis, but still skywave

Who would have thought Savage's thread would still be here after all this time and years after AM IBOC had been dead as a door nail? I only get the occasional buzz at night now here in Ma. WBZ, Savage's potential nemesis turned it off at night several years ago, I'm not sure if it's still on during the day time (might as well waste some electricity though). I believe WINS 1010 is still pretty much the only AM station that is a consistent PITA here at night. There are a few others, WCBS occasionally, WTIC 1080 still hashes up the place sometimes although it's not that strong here. It makes me wonder why these last few big AM stations keep it turned on? Even WOR 710, the flagship for the jammer turned it off several years ago. I remember years ago a lot of us were waiting and hoping ibiquity would publicly throw in the towel and we could have a celebration but this slow drawn out fizzle was better than nothing I guess, at least AM DXing is OK except for the rising tide of digital hash, can't win for losin'. At night here during the winter with long tuned dipoles and a phase shifter though it's still possible to pick up both European LW and MW signals.

KB1OKL said:

I remember years ago a lot of us were waiting and hoping ibiquity would publicly throw in the towel and we could have a celebration but this slow drawn out fizzle was better than nothing I guess, at least AM DXing is OK except for the rising tide of digital hash, can't win for losin'.

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Ibquity never threw in any towels, certainly not because of a handful of cranky DX'ers. The primary reason AM stations stopped doing AM IBOC was due to the original exciters dying of old age, with no support from the original manufacturers. Essentially these AM HD exciters were nothing more than a PC with spinning hard drive. Once the stations stock of main and space exciters finally gave up the ghost, stations had few options for continuing.

Kelly A said:

Essentially these AM HD exciters were nothing more than a PC with spinning hard drive. Once the stations stock of main and space exciters finally gave up the ghost, stations had few options for continuing.

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I wonder how much longer until the rest of the HD exciter's hard drives would be doing this when someone attempts to power them on?

https://www.youtube.com/watch?v=3WnzrnL8oKA

https://www.youtube.com/watch?v=Gryqa0UoTmI

The original AM IBOC exciters were pretty much one-off/prototypes. They were developed as a trial for the interest of testing AM-HD.

Just as with manufacturers like GatesAir recently announcing it will discontinue building AM transmitters, even back then, interest in a future for AM transmission products was in decline.

I just noticed WSCR (670) and WBBM (780) started coming in with a HD carrier a few months ago. I live in central Mississippi, so it's all skywave for me. HD lock almost never happens. My car radio did pull in WBBM with a HD lock one night. I've been hoping WSM (650) and WWL (870) would go HD. I might have a pretty good chance of getting a HD lock with those.

rbc said:

I just noticed WSCR (670) and WBBM (780) started coming in with a HD carrier a few months ago. I live in central Mississippi, so it's all skywave for me. HD lock almost never happens. My car radio did pull in WBBM with a HD lock one night. I've been hoping WSM (650) and WWL (870) would go HD. I might have a pretty good chance of getting a HD lock with those.

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Unlike FM-HD transmission equipment, AM HD exciters, importers, etc. are not really available to purchase anymore. Most if the original AM-HD gear is based on a PC, including software and custom made one-off hardware. For stations that are still broadcasting AM-HD, they purchased enough spare gear to keep it running. Once that transmission gear dies, stations go back to analog only due to lack of manufacturer support.

Another barrier for AM stations, is their antenna system. Some of the older antenna and phasing equipment can't provide enough bandwidth to support the digital sidebands. In many cases, broad-banding directional AM transmission antenna systems either can't be done due to the limits of physics, or would be cost prohibitive.

Kelly A said:

Unlike FM-HD transmission equipment, AM HD exciters, importers, etc. are not really available to purchase anymore. Most if the original AM-HD gear is based on a PC, including software and custom made one-off hardware. For stations that are still broadcasting AM-HD, they purchased enough spare gear to keep it running. Once that transmission gear dies, stations go back to analog only due to lack of manufacturer support.

Another barrier for AM stations, is their antenna system. Some of the older antenna and phasing equipment can't provide enough bandwidth to support the digital sidebands. In many cases, broad-banding directional AM transmission antenna systems either can't be done due to the limits of physics, or would be cost prohibitive.

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That's unfortunate. It seems like the consumer radios with AM HD are finally getting some traction. Hopefully, the transmitter manufacturing will catch up now.

Kelly A said:

Unlike FM-HD transmission equipment, AM HD exciters, importers, etc. are not really available to purchase anymore. Most if the original AM-HD gear is based on a PC, including software and custom made one-off hardware. For stations that are still broadcasting AM-HD, they purchased enough spare gear to keep it running. Once that transmission gear dies, stations go back to analog only due to lack of manufacturer support.

Another barrier for AM stations, is their antenna system. Some of the older antenna and phasing equipment can't provide enough bandwidth to support the digital sidebands. In many cases, broad-banding directional AM transmission antenna systems either can't be done due to the limits of physics, or would be cost prohibitive.

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It looks like Nautel has an AM HD broadcast product line:

http://www.nautel.com/solutions/digital-radio/hd-radio/

Is that vaporware, or is it a more matter of competition and a 2nd hand market not really existing yet? The antenna and feed line is a different matter. I'm not a broadcast engineer but I've dealt with HF feed lines and antennas with amateur radio. I could see how the costs could mount if you need to update your antenna systems.