• Get involved.
    We want your input!
    Apply for Membership and join the conversations about everything related to broadcasting.

    After we receive your registration, a moderator will review it. After your registration is approved, you will be permitted to post.
    If you use a disposable or false email address, your registration will be rejected.

    After your membership is approved, please take a minute to tell us a little bit about yourself.
    https://www.radiodiscussions.com/forums/introduce-yourself.1088/

    Thanks in advance and have fun!
    RadioDiscussions Administrators

(USA) High Power AMs

kfbkfb

kfbkfb

Listening to WLS AM in the mid-1980s, sometimes people would call in from a long distance away saying they were regular listeners, the afternoon "talk" show hosts (IIRC, Steve Dahl and Gary Meyer) would generally thank them but also occasionally say that long distance listeners weren't included in WLS AM ratings.

With easy streaming of most (all?) (USA) AM radio stations, is high transmitter power (50kW) for long distance reception economically justifiable?


Kirk Bayne
 
Yes, if that 50KW AM station still wants their OTA signal to overcome the increased level of RFI that's nearly everywhere. A lot of people still listen to OTA radio.
 
kfbkfb said:
With easy streaming of most (all?) (USA) AM radio stations, is high transmitter power (50kW) for long distance reception economically justifiable?
Click to expand...
Today, the only reason for medium power levels like 50,000 watts is to overcome man made noise in a larger metro area.

Even then, in places where the ground conductivity is poor, 50 kw is not enough to cover well and noiselessly a large metro area. WSB in Atlanta is an example of such a station.

Night skywave coverage is not of any commercial signficance and has not been for decades, partly because most radio listening is done in the 6 AM to 7 PM time period, not at night.
 
Operating WSB 750 with enough power for me to hear it in Indianapolis probably isn't worth it, but the cost of operating the transmitter is a pittance compared to the total operating expenses of a broadcast facility.
 
PTBoardOp94 said:
Operating WSB 750 with enough power for me to hear it in Indianapolis probably isn't worth it, but the cost of operating the transmitter is a pittance compared to the total operating expenses of a broadcast facility.
Click to expand...
Maybe in larger markets but some of the sub 100 markets stations' AM's have to downgraded. Example WKNG had 50KW daytime (5 KW critical) went to 15 KW daytime still 5kw critical, of course they had an FM translator.

IIRC one time WLOR the old WAAY Huntsville AL had more than 44 watts at night. There was a rumor that they were going from 50KW directional to something non directional but I can't find it on the FCC site. This info came from a 1550 Smyrna GA source. Again they have a FM translator in Huntsville.
 
The place where a 50kw pays for itself with its night signal is in the months where sunrise is after 6:00 a.m. and sunset before 7:00 p.m. That puts you on night pattern, lowered power or both during part of both your morning and afternoon drive shows. For example, here in Sacramento, in December, you'd be on night pattern and/or night power from 4:45 in the afternoon until 7:15 in the morning. And from September through March, at least some part of one or both drive times would be affected.

In most sizeable metro areas, that signal would be inadequate. So being 50kw day and night, non-directional, protects your biggest revenue dayparts.
 
Funny how in the late 60's an into the 70's the FCC and others were looking into the feasibility of increasing the power of some of the Class 1A clear channel stations to 750 kw! But of course it never happened.
 
TomasEstefan said:
Funny how in the late 60's an into the 70's the FCC and others were looking into the feasibility of increasing the power of some of the Class 1A clear channel stations to 750 kw! But of course it never happened.
Click to expand...
Imagine if that actually happened, coast to coast reception at 750 kw! They might have never torn down the clear-channels if this passed, however I would see a lot of chain-link fences arcing badly. On the bright side, Californians could be listening to WABC at night easily.
 
TomasEstefan said:
Funny how in the late 60's an into the 70's the FCC and others were looking into the feasibility of increasing the power of some of the Class 1A clear channel stations to 750 kw! But of course it never happened.
Click to expand...
After WW II, the group of clear channel broadcasters engaged in about 20 years of lobbying before the FCC and Congress to get powers increased to the 500 to 750 kw levels.

WSM: The campaign for 750,000 watt AM stations documents much of the activity of the Clear Channel Broadcasting Service.

As the decade of the 60's ended, the FCC began considering allowing secondary 50 kw stations on the clears, and the idea of increased power for the existing stations was finally quashed.
 
ZantennaG1 said:
Imagine if that actually happened, coast to coast reception at 750 kw! They might have never torn down the clear-channels if this passed, however I would see a lot of chain-link fences arcing badly. On the bright side, Californians could be listening to WABC at night easily.
Click to expand...
While 750 kw might have given reliable coverage of much of the nation, it would not have been reliable consistently. And daytime, such a station would not even quadruple the coverage of a 50 kw station. So, let's say, WCAU in Philadelphia had gone to 500 kw on 1210... its daytime coverage would not even consistently be highly listenable in Pittsburgh.

And by the end of the 50's, nighttime radio had lost its importance as TV took over the American home. So increased night coverage had little value while the cost of increased day coverage was not worth it.

In the later 60's, I often tried to pick up Transworld Radio from Bonaire in Quito, Ecuador... almost exactly 1000 miles away. Even using my Hammarlund HQ-180 and a loop antenna, I never could hear it in the daytime. TWR had 500 kw at 800 kHz. The distance is the same as New York City to Chicago, so one can see that those high powers might have covered a significant region, but not large portions of the whole nation.
 
DavidEduardo said:
After WW II, the group of clear channel broadcasters engaged in about 20 years of lobbying before the FCC and Congress to get powers increased to the 500 to 750 kw levels.

WSM: The campaign for 750,000 watt AM stations documents much of the activity of the Clear Channel Broadcasting Service.

As the decade of the 60's ended, the FCC began considering allowing secondary 50 kw stations on the clears, and the idea of increased power for the existing stations was finally quashed.
Click to expand...
Today, as much as back then, finding that line between rural coverage and monopolization has been a balancing act. I bet people were pretty worried that with the 750kw stations, the locals would have no room. Despite that, I think the FCC still could've set aside a local class, while having a 750kw tier of clear channel, and a 50 or 100kw tier.
 
Kelly A said:
Depends on what you consider a lot. AM listening has been in an increasing downward spiral for the past twenty years.
Click to expand...
Make that more like 45 years, give or take.

1977 was the year where the national average showed more listening to FM than to AM. And if one looks at music formats, the breaking point was about 1975.
 
DavidEduardo said:
While 750 kw might have given reliable coverage of much of the nation, it would not have been reliable consistently. And daytime, such a station would not even quadruple the coverage of a 50 kw station. So, let's say, WCAU in Philadelphia had gone to 500 kw on 1210... its daytime coverage would not even consistently be highly listenable in Pittsburgh.

And by the end of the 50's, nighttime radio had lost its importance as TV took over the American home. So increased night coverage had little value while the cost of increased day coverage was not worth it.

In the later 60's, I often tried to pick up Transworld Radio from Bonaire in Quito, Ecuador... almost exactly 1000 miles away. Even using my Hammarlund HQ-180 and a loop antenna, I never could hear it in the daytime. TWR had 500 kw at 800 kHz. The distance is the same as New York City to Chicago, so one can see that those high powers might have covered a significant region, but not large portions of the whole nation.
Click to expand...
The 750kw would just be for nighttime theoretically, right? But even a tenfold increase of power (50 to 500) should be an improvement of distance, even if it doesn't necessarily mean it sounds better locally.
 
ZantennaG1 said:
The 750kw would just be for nighttime theoretically, right? But even a tenfold increase of power (50 to 500) should be an improvement of distance, even if it doesn't necessarily mean it sounds better locally.
Click to expand...
No, the idea was 500 to 750 kw day and night for the 1-A clears (under the old classification). But in some cases, such as KDKA on 1020 and WBZ on 1030, there would not have been enough separation for the full power. Or 760 in Detroit and 770 in NYC and 780 in Chicago. None of the three could have gotten "full power" due to adjacent channel overlap.

Ones like Rochester's 1180 would have had to worry about 1190 in Ft Wayne and 1170 in relatively nearby Wheeling... and that is just one example.

And for the 1-B stations, most would have been lucky to go from 50 kw to 100 kw, with considerable directionality involved.

Again, with TV taking over the living room in the mid-50's, the increased night coverage no longer looked attractive.
 
DavidEduardo said:
No, the idea was 500 to 750 kw day and night for the 1-A clears (under the old classification). But in some cases, such as KDKA on 1020 and WBZ on 1030, there would not have been enough separation for the full power. Or 760 in Detroit and 770 in NYC and 780 in Chicago. None of the three could have gotten "full power" due to adjacent channel overlap.
Click to expand...
Not to mention Canada. It is my understanding that a significant reason why higher AM power did not happen is that the NARBA signatories could not agree on how to make it happen.
 
An example of a "super power" AM broadcast can be heard in Europe - 2,000kW right at the bottom of the dial on 540 out of Hungary. Hungary itself is about the size of Indiana. Listening on various SDR receivers around Europe, the signal can be heard in daytime as far away as Germany, but it's not listenable, and it wouldn't penetrate urban areas in any meaningful way beyond Hungary. At night, it covers much of Europe, but it's plagued by AM fading and I doubt there are many Hungarian ex-pats tuning into it when all the national media is available online.

In short, mega power looks good on paper, but the results (especially considering the hugely increased energy costs) can be underwhelming. You don't get a huge amount more useful coverage from 2,000kW than you do from 100-200kW.
 
PTBoardOp94 said:
Not to mention Canada. It is my understanding that a significant reason why higher AM power did not happen is that the NARBA signatories could not agree on how to make it happen.
Click to expand...
Yet Mexico had several 250,000 watt stations, a couple of 150 kw operations, and quite a few 100 kw ones. And they were in NARBA.

Many of those have reduced power since then, including 730, 900, 940, 1570, 540, 1570 and 800.
 
DavidEduardo said:
Yet Mexico had several 250,000 watt stations, a couple of 150 kw operations, and quite a few 100 kw ones. And they were in NARBA.

Many of those have reduced power since then, including 730, 900, 940, 1570, 540, 1570 and 800.
Click to expand...
What is 1570 XERF's current night power?
 
Status
This thread has been closed due to inactivity. You can create a new thread to discuss this topic.


Back
Top Bottom