Saving Electricity

[secondchoice]

I was just wondering if a high band AM transmitter (5 kw daytime) would save any electricity if the modulation was dialed back to 50% modulation. The only purpose for this rig is to make a translator legal. I believe lower modulation would make the finals last longer Has anybody done this?

Nobody is listening to the AM. The STL (FM radio tuned to the translator) was down for ??? The manager did an occasional meter check via phone but never listened. The controler is working signing it on an off at the correct times. If the silence detector took it off and nobody answered the call IDK. There is a P.O.T. line out there for the alarm system. The power usage last month was 25% lower than last year according to the power CO-OP.

I feel like Sargent Sholtz on Hogan's Hero's: "I see nothing!!"

 

[davideduardo]

I was just wondering if a high band AM transmitter (5 kw daytime) would save any electricity if the modulation was dialed back to 50% modulation. The only purpose for this rig is to make a translator legal. I believe lower modulation would make the finals last longer Has anybody done this?

It's not going to save a lot of money. The transmitter has to produce the carrier and unless you have the advances surpressed carrier system, that is more than half the cost. Lower modulation will save a few pennies, but what I'd recommend is set positive peaks at 90% and don't use a lot of compression on the AM audio feed. Highly compressed audio maintains very high modulation levels and does increase cost.

Nobody is listening to the AM. The STL (FM radio tuned to the translator) was down for ??? The manager did an occasional meter check via phone but never listened. The controler is working signing it on an off at the correct times. If the silence detector took it off and nobody answered the call IDK. There is a P.O.T. line out there for the alarm system. The power usage last month was 25% lower than last year according to the power CO-OP.

You can save a few dollars with reduced intensity of modulation and setting the peak limiter to 85% to 90%.

You say you have finals, so that means a tube rig and likely high level plate modulation, so the whole rig is not very efficient. You will save most by making sure that you are not highly compressing, and then setting the peaks to a bit under 90% or so.

I feel like Sargent Sholtz on Hogan's Hero's: "I see nothing!!"

And I don't want to see an old tube transmitter ever again!

Last AM I was at was 100 kw, with a totally solid state Nautel. Consider getting a new rig (not everyone makes AM rigs any more) as over time it will save you a lot.

(Trying to give a non technical answer. I used to build those tube transmitters myself, and don't want to go back!)

 

[Kelly A]

Not to go down a radio rabbit hole, but I was just thinking about this topic the other day. Many years ago I had a Collins 828 D "Power Rock" that was a main TX and the newer equivalent version the Continental 315R-1 as a backup. Obviously, both tube transmitters, but none of the solid-state AM transmitters from Nautel, BE, or Harris/Gates could come close to the way the old Power Rock's could modulate. Sure, solid state AM transmitters require less maintenance and power, but they can't come close to the on-air performance of certain tube boxes of the day.

 

[spt87]

Sad, one way to guarantee no one will listen is to make it sound like garbage.

Personally I think the FCC should make FM translators rebroadcast the off air AM audio. That would revitalize AM - station owners would need to put out decent audio in stereo on their AM. If the AM goes off air the FM automatically loses its feed so no concern about running the translator illegally.

 

[fybush]

Sad, one way to guarantee no one will listen is to make it sound like garbage.

Personally I think the FCC should make FM translators rebroadcast the off air AM audio. That would revitalize AM - station owners would need to put out decent audio in stereo on their AM. If the AM goes off air the FM automatically loses its feed so no concern about running the translator illegally.

Even overlooking some of the regulatory flaws in your idea - what about daytimers that are allowed to keep their translators on the air at night? Or AM stations whose translators can be up to 25 miles away, often far outside the AM station's usable coverage? - this is the kind of idea that you'd only come up with if you've never been at an FM translator site.

These are usually terrible spots for AM reception. You're surrounded by all kinds of RF, both intentional and noise. You're often at the mercy of a commercial landlord who's more than happy to add significantly to your rent for the extra space you'd need to install an AM loop receive antenna.

You could have the most pristine audio coming out of your "originating" AM and it's still highly unlikely that whatever you can receive for rebroadcast at your translator site is going to be pleasant to listen to.

If the goal is to make AM audio better, then regulate THAT directly. Trying to back-door something like this isn't the answer.

 

[SomeRadioGuy]

Sad, one way to guarantee no one will listen is to make it sound like garbage.

Personally I think the FCC should make FM translators rebroadcast the off air AM audio. That would revitalize AM - station owners would need to put out decent audio in stereo on their AM. If the AM goes off air the FM automatically loses its feed so no concern about running the translator illegally.

thats a disaster waiting to happen

What if you cant pick up the AM at the translator site at night and have trouble during the day due to man made noise, etc?

(I worked for an AM with translator that wouldnt be able to do what you propose well at all and @fybush has been out to the site with me)

And no matter how well you process the AM itll never sound as good as rich, bass-y FM Stereo. Youll turn listeners off

 

[Kmagrill]

An AM transmitter operating at 100% positive modulation is actually operating at that instant at 150% of power. So, a 1kW transmitter is operating at 1.5kW at 100% modulation. I've known of AM engineers for years that have reduced power and/or modulation levels to save electricity and wear on the equipment. Of course, we always joked that the most savings is achieved by turning off the transmitter.

However, there is another option called MDCL (Modulation Dependent Carrier Control). It's been used for years in some transmitter lines and was finally approved by the FCC a number of years ago. Basically, at high modulation levels, MDCL reduces the carrier level by up to -6dB and simultaneously adjusts the modulation to maintain relative 100%. So, that 1kW station at 100% modulation actually puts out 500W of carrier and 250W of modulation power for a total of 750W. This is known to save as much as 40+% on the power. Broadcast Electronics showed a soon-to-be-released MDCL controller in an external box at the NAB that could, in theory, work with almost any transmitter. I'm sure that some additional engineering would be required, especially for an older tube type transmitter.

 

[secondchoice]

Sad, one way to guarantee no one will listen is to make it sound like garbage.

Personally I think the FCC should make FM translators rebroadcast the off air AM audio. That would revitalize AM - station owners would need to put out decent audio in stereo on their AM. If the AM goes off air the FM automatically loses its feed so no concern about running the translator illegally.

The two problems with that idea I see is:
#1The AMs will most likely go digital and still you have cut out of the digital stream during thunder and lightning storms.
#2 If you are a daytime with no nighttime service how are you going to "feed" the FM translator?

 

[Kelly A]

Sad, one way to guarantee no one will listen is to make it sound like garbage.

Personally I think the FCC should make FM translators rebroadcast the off air AM audio. That would revitalize AM - station owners would need to put out decent audio in stereo on their AM.

Wait, making your FM translator audio sound inferior (like poo) would help AM? What kind of pretzel logic is that?

If the AM goes off air the FM automatically loses its feed so no concern about running the translator illegally.

Or even better, keep your AM station up and running!

 

[AlligatorClipz]

MDCL does work quite well. The more frequent modulation there is, the more the carrier is reduced, and the more electricity is saved. MDCL is more effective on higher power stations, because typically the AC to RF conversion efficiencies on larger transmitters are higher. Also, stations which run on 240 or 480 volts three phase are typically paying a different rate than those on a 120/240 volt single phase service.

Edited to add...
Nautel calls there feature MDCL, Modulation Dependant Carrier Level. It is a software option on NX line transmitters.

GatesAir calls it ACC, Active Carrier Control. It is a retrofit board that can be installed in DX series transmitters.

This document from GatesAir describes the technology clearly. https://www.gatesair.com/documents/slides/2015-07-Anderson-Application-of-MDCL-Control-Tech.pdf

 

[bigdonho]

Even overlooking some of the regulatory flaws in your idea - what about daytimers that are allowed to keep their translators on the air at night? Or AM stations whose translators can be up to 25 miles away, often far outside the AM station's usable coverage? - this is the kind of idea that you'd only come up with if you've never been at an FM translator site.

These are usually terrible spots for AM reception. You're surrounded by all kinds of RF, both intentional and noise. You're often at the mercy of a commercial landlord who's more than happy to add significantly to your rent for the extra space you'd need to install an AM loop receive antenna.

You could have the most pristine audio coming out of your "originating" AM and it's still highly unlikely that whatever you can receive for rebroadcast at your translator site is going to be pleasant to listen to.

If the goal is to make AM audio better, then regulate THAT directly. Trying to back-door something like this isn't the answer.

Maybe the FCC should go back to requiring annual proof of performance measurements. Tuning across the AM band in south Florida, I hear stations with hum and buzz, horrible distortion, audio being clipped, terrible frequency response. Just basically sounds like crap.

Or, would this be too much job killing regulation?

 

[Kelly A]

Maybe the FCC should go back to requiring annual proof of performance measurements. Tuning across the AM band in south Florida, I hear stations with hum and buzz, horrible distortion, audio being clipped, terrible frequency response. Just basically sounds like crap.

Or, would this be too much job killing regulation?

Given all the media landscape regulated under the FCC, do you think the Commission cares if you have hum in your AM station audio?

 

[spt87]

Hmm, good point about night time operation.

I thought the translator was to duplicate the AM coverage area, at least as far as the AM "improvement" authorized translators go. If the translator site can not pick up the AM over the air it would seem it is extending the coverage, not duplicating it. I suppose there are some translators which are authorized to fill in gaps, though, and were not part of the improvement effort.

Yes, this is a backdoor method to address the AM audio quality which could be done more directly. My thought was the regulators tend to like simple rules so requiring rebroadcast of the over the air AM signal would incentive owners to maximize AM audio quality without having specify or enforce some audio performance rules. To add regulation differently, use the AM for Every Vehicle Act to put some requirements on broadcasters for audio quality as well as on the receiver makers. It would be a gift back to all the people who have supported that act.

As for receivers, supposedly this is a "system" so I think it is perfectly reasonable to put requirements on the receiver makers so that end of the system works as it should. It was done in the past for FM and UHF TV - time for AM to get some similar help.

Bass heavy FM vs AM? Seems like processing has more to do with that than the band. There is an AM near me (WNBH) running classic hits and it is REALLY bass heavy. Its FM translator is not. The AM sounds good on my wide bandwidth Sony AM Stereo boombox though (the AM is mono) with my bass and treble adjustments. Another example, WJIB, the AM sounds equal to or better than its FM translator with great frequency response highs to lows on the AM.

 

[secondchoice]

I am sure there are exceptions for high powered AM's in good ground conductivity areas but around here in North GA with some of the worst conductivity, most Class Ds and Cs use the "25 mile rule" for there FM translator 60 db coverage.

 

[Kelly A]

Hmm, good point about night time operation.

I thought the translator was to duplicate the AM coverage area, at least as far as the AM "improvement" authorized translators go. If the translator site can not pick up the AM over the air it would seem it is extending the coverage, not duplicating it. I suppose there are some translators which are authorized to fill in gaps, though, and were not part of the improvement effort.

FM translators tied to AM never actually exceed the theoretical coverage of their AM sister. That's part of the problem.

Yes, this is a backdoor method to address the AM audio quality which could be done more directly. My thought was the regulators tend to like simple rules so requiring rebroadcast of the over the air AM signal would incentive owners to maximize AM audio quality without having specify or enforce some audio performance rules.

But physics and modern realities of bandwidth limitations dictate that AM can't reproduce the quality or lower noise floor of FM listening.

 

[davideduardo]

FM translators tied to AM never actually exceed the theoretical coverage of their AM sister. That's part of the problem.

But in many cases an AM that is highly directional at night may finf tat its translator does a fine job in filling the null area of that DA operation.

 

[fybush]

I want to clarify something here that a lot of posters aren't getting right.

The translator service for AM stations was never meant to be an inch-for-inch exact coverage map to AM coverage. Given all of the vagaries of AM coverage, that would be an impossible task. You have everything from low-dial AM boomers in the plains that cover hundreds of miles by day to high-dial 250-watters that are lucky to get out for 10 miles, you have DA restrictions, and you have the change in coverage from day to night facilities.

The original rules for AM translators made it more or less a fill-in service - the translator's 60 dBu could not exceed the greater of the AM's daytime 2 mV/m or a 25-mile radius from the AM site. Even then, you could situate a translator 20+ miles away from the AM in an area that the AM didn't cover well, or at all, and it would have been legal.

That has changed as the service has evolved. You can now go even more than 25 miles as long as it's within the 2 mV, so a station like WNAX or KFYR with a huge 2 mV signal could put a translator 100 miles away.

A translator of a small AM signal can absolutely cover much more than the AM itself, as long as it's contained within that 25 miles. Compare WRSB, a 300-watt daytimer on 1600 out on the western edge of Monroe County, with its translator W248BH, a 250-watt signal 138 meters above ground on the tallest building in downtown Rochester. The two signals barely overlap at all (and that's legal, because of the 25-mile rule) and the translator covers something like 10x the population the AM does.

The WRSB AM signal does not exist, at all, at the W248BH translator site downtown. And, again, that's perfectly legal under the current rules. There's a fiber internet feed to the translator. There's no way that translator could be fed by the AM off-air.

Another example on the other side of town is WCGR, a 250-watt daytimer on 1550 in Canandaigua, 25 miles or so southeast of Rochester. It has two translators, one aimed at the east side of Rochester (W261DR) and one serving the Canandaigua area from Bristol Mountain (W283BF), both with much better coverage than the anemic little AM "parent."

 

[Kelly A]

I want to clarify something here that a lot of posters aren't getting right.

The translator service for AM stations was never meant to be an inch-for-inch exact coverage map to AM coverage. Given all of the vagaries of AM coverage, that would be an impossible task. You have everything from low-dial AM boomers in the plains that cover hundreds of miles by day to high-dial 250-watters that are lucky to get out for 10 miles, you have DA restrictions, and you have the change in coverage from day to night facilities.

Okay, given all that, what percentage of AM stations with FM translators do you estimate to have their translator coverage matching or exceeding the AM theoretical 5MV/m coverage day or night? Let's use a conservative field strength of 34DBu for the translator.
5%? 25%?

 

[formerradio]

I was just wondering if a high band AM transmitter (5 kw daytime) would save any electricity if the modulation was dialed back to 50% modulation. The only purpose for this rig is to make a translator legal. I believe lower modulation would make the finals last longer Has anybody done this?

Nobody is listening to the AM. The STL (FM radio tuned to the translator) was down for ??? The manager did an occasional meter check via phone but never listened. The controler is working signing it on an off at the correct times. If the silence detector took it off and nobody answered the call IDK. There is a P.O.T. line out there for the alarm system. The power usage last month was 25% lower than last year according to the power CO-OP.

I feel like Sargent Sholtz on Hogan's Hero's: "I see nothing!!"

If you are in a very small market maybe review your signal coverage of your town. If you can lower power to 500 watts and still cover all of your city of license you file an application to reduce power.

 

[Kelly A]

If you are in a very small market maybe review your signal coverage of your town. If you can lower power to 500 watts and still cover all of your city of license you file an application to reduce power.

Then in that case, you should reduce the coverage of your translator to match. As an intentional AM operator, you're in for a penny, in for a pound.