Help getting started as a new low power AM broadcaster

If you're going to have your mixer etc. in the basement and feed audio from it to your transmitter, why do you need the computer at the transmitter site? Or am I missing something.

Overall, sounds good. Experimentation is the key to get the best sound and the best signal. The Talking House, combined with an ATU is a good choice; that and the ChezRadio ProCaster are probably the two best plug and play options. From all accounts the SSTran is a good choice but you're going to have to put a kit together, certainly not plug and play. I've achieved the best results with a Hamilton Rangemaster mounted at ground level, coupled with an Inovonics 222, but the Talking House and ProCaster were not too far behind in terms of sound quality and range. The ProCaster has built in audio processing and they now claim to support asymmetric modulation (I have an older model which did not do this).

Your last question opens up a huge can of worms - while it is legal to have an elevated transmitter, you must still meet Part 15 guidelines, which state that the antenna, feedline and ground lead must be no longer than 10 feet (3 meters). The ground for an elevated mount is a gray area at best, and is subject to interpretation by pretty much all the posters here, as well as FCC inspectors.

The only thing I would suggest is to try the ground mount first - if you can get that to work satisfactorily, you won't have to even worry about elevated mounts, ground leads and the like. If you can't, then you can wade into the entire elevated mount morass.

Hope that helps a bit.

I just realized that I didn't answer your basic question.

No, there is really no basic reference for Part 15 broadcasting. This Forum is a good place to start reading.

You might also want to consider joining the ALPB (Association of Low Power Broadcasters), which is holding a meeting this Friday - see the thread announcing it for details on how to join in. The ALPB was formed to assist both new and existing Part 15 broadcasters in their endeavors.

What I think I've learned from the several well trained radio engineers who have shared their knowledge here on the site is that the best of all possible coverage can be found with a ground level transmitter installed out, away from obstacles on open ground, with buried ground radials.

The reason for this is that AM radio signals propagate by following the ground, an advantage that is diminished by raising the antenna up in the air.

I believe that the only reason to ever mount a transmitter up high is when there is no other choice.

I am unsure where the final transmitter site will end up, so flexibility in what gets bundled with it. Eventually will be pushing content to remote transmitter sites where the computer need will be more clear. Less prone to microwave downtimes, bandwidth blips, etc. Planning on pumping content to broadcast installations via whatever mechanism we can get to work (wifi, wireless, cellular, etc.). So, not great for live broadcasting (delays, drops, etc.) but fine for fetching files.

The computer is basically a Swiss army knife of audio sorts. Think Barix-like functionality. On board Compact Flash or USB for storing files. Those files ideally are the majority of the content broadcasted. Exceptions would be live shows. Also could accomplish some audio post-processing as-needed.

I like the Procaster and the SSTran, the Pro is too rich for my pocket to get started. The SSTran has the assembly issue which is a barrier. Cost cost on that goes up above the TH considerably. The TH ATU luxury is something I plan on working around since they are pricey and hard to find.

Planning the ground mount first 🙂 The 3 meter (antenna, feedline, ground) make little sense to me when the Procaster and other outdoor units are being mounted way up high. Being new to this, obviously overlooking something as to how they are compliant.

Carl,Carl. Your voice keep blaring out of my tech phone device that doubles as a MP3 player.

Low Power Hour has been my listening for days on end now 🙂 Thanks for all you do.

I thought the AM signal hugged the ground. Had a conversation with an amateur radio fellow who seemed to think there is a need to raise the antenna, even if it is in a building.

Admittedly, I am above my head on disputing the fine details of this 🙂

Sounding like my empty lot (doubles as a mini farming experiment) would probably be where the transmitter should go. It's a mega high density urban zone I am in boxed by power lines and border by brick streets long ago covered with asphalt. Vertical obstructions consist of two large trees cleared under the first 15 feet up. Plenty of earth and sky though.

Neighboring properties consist of a few hundred feet of empty lots in one direction at same grade level (south). North is a hedgeline and one house in 200 feet. West is 2 story old housing with a downward slope to river. East is a 8 foot incline and two of our big brick structures. Does that sound too challenging?

The 3 meter (antenna, feedline, ground) make little sense to me when the Procaster and other outdoor units are being mounted way up high. Being new to this, obviously overlooking something as to how they are compliant.

Below is a link showing the performance difference between earth-level and elevated mounting, other things equal.

When the "ground" terminal of the elevated transmitter+whip has a conducting path through a short "ground lead" to another conductor leading to an earth ground (something buried in the earth), then that entire conducting path becomes a radiating part of the antenna system.

It isn't the height of the 3-m whip that produces greater coverage by an elevated mounting, but the added length of the radiating conductors in the path to r-f ground.

Apologies to those who've seen/read all this many times before.

The point Rich makes is a vital one and after taking every side on the issue I have become convinced, at least for today, that the ground lead limitation of 15.219 is a major obstacle for elevated installations.

The comments and rebuttals on the topic fill a year-and-a-half of solid reading on this site alone.

Therefore a ground level installation is doubly recommended so as to avoid the uncertainties encountered by height.

The advice of placing the antenna high is perhaps best applied to FM and the very high frequencies.

One thing I would do is start
simple - for the beginning
anyway.

I'd get the transmitter running
and feed it with audio via just
a cable (even a temporary one,)
and I always did the same with
power for the transmitter - the
18 volts for my SS-Tran went out
to the back yard via a cable.

Then just get a music source via
a computer or CD player or something
and run it into the cable going
outside. You will probably want some audio
processing and maybe some equalization.
And I suppose your mixer would be
helpful. You will need the correct
audio levels anyway, or close to them
to start.

I guess there are software EQ and audio
processor programs. I think, anyway.

You sure know a lot more than I did when
I started this.

If you start simple, it will be a lot
easier to troubleshoot things if you
have to. Then you can add what you
want. I have had many times where
I have had complicated Part 15
set-ups that had problems - and I
would tear a whole bunch of stuff
apart - only to find a loose connection
or a single bad audio cable.

I have to think about some of your
other issues. If I can come up with
anything useful, I will sure post it.

Believe me, there is nothing like
flicking that switch in the house
and hearing a good solid AM carrier
come on through your air monitor.
Especially if your transmitter is
way out in the back yard like mine
was.

Good luck. We'll be thinking about you.

Bruce, W 60 HZ, 1020 kHz AM Carrier Current,
X-13, 13.560 MHz Experimental, and other
Part 15 explorations

My present transmitters are close to the house (AMT3000 and AMT5000) but I plan redundant transmitters as far out in the yard as possible, for that thrill of hearing my signal return from "far away".

I am working on the design of a remote control panel so all the carriers can be controlled from a single location.

It is most likely that both far out transmitters will be AMT5000s.

I also have a second AMT3000 dedicated to indoor antenna experimentation, for the benefit of those who only want good indoor reception.

Thinking and talking about these projects is part of the fun, so I am not in any hurry to finish, but progress is taking place.

An elevated mount is not as simple as it's being made out to be. The advantage is minimizing obstructions, the disadvantage is grounding or lack thereof. But a long ground wire does not have to radiate, you can add a choke to minimize any potential radiating. And at least one poster here reported an INCREASE in range when he removed his ground. There are alternative methods of grounding, such as radials on a flat roof, or mounting above a metal roof. You have to experiment.

But overall I agree with Carl, the safest way is to ground mount. As far away as possible from signal absorbing obstructions. I've achieved good results with the Rangemaster and Procaster, both ground mounted.

It IS possible to add radials up on a pitched roof, that is, a common "A-frame" type roof.

By centering the vertical mast in the center of the top most peak, a pair of radials can be equally divided on both sides running the entire top roof-ridge. But the rest is not simple.

The cross-radials extending over the drop-portion of the roof must be held parallel by dedicated mounting posts around the outer boundaries.

Having radials all over the place, many suspended in the air, would make roof maintenance work a little awkward, maybe dangerous.

The point is, it IS possible.

The only missing ingredient with such a system would be an earth safety ground.

In other discussion forums I've seen claims that lightning arresters can be used for safety and compliance, but to my knowledge this has never been discussed here.

An elevated mount is not as simple as it's being made out to be. The advantage is minimizing obstructions, ...

Nothing personal, but just to note that the groundwave signals of MW broadcast stations suffer very little additional loss with respect to their theoretical values for given paths without obstructions, even after traveling across a large city full of physical obstructions that completely block the line-of-sight paths from the transmit antenna to receive antennas at those locations.

This is supported both by experience, and the "signal strength" display of modern, DSP-based MW receivers such as the Tecsun PL-310, which show the same signal strength on both sides of a typical suburban home, along the radial line back to the transmit site.

The reason for this is that the vertical dimensions of such structures are much smaller than the transmitted wavelength.

The same is true for Part 15 AM installations, although due to their much lower radiated power their useful path lengths will be much shorter.

But a long ground wire does not have to radiate, you can add a choke to minimize any potential radiating.

Yes, but if such a choke is successful in preventing MW radiation from a long ground wire, then Part 15 AM operators would be better off installing their transmitter+3-m whip with its chassis a few inches above the earth, and using an "unchoked" conducting path to r-f ground (something buried in the earth).

I'm not speaking theoretically, Rich, but from practical experience with Part 15 installations.

Obstructions such as houses, close to a ground mounted transmitter, absorb the miniscule signal that is being transmitted, and you get shortened range along those paths.

Elevate the transmitter, even eliminate the ground, and the range is increased along those previously shortened paths. The problem is that if you eliminate the ground, your range along the other paths is also shortened, as your overall signal is somewhat weakened.

No question that if you have no obstructions (or those that exist are at some distance from the antenna), a ground mount is the best choice. And for simplicity and legalities, at least in the U.S., I would definitely go with a ground mount first. Only if range is unacceptable would I consider some form of elevated mount, and only after careful consideration of the Part 15 rules, as well as safety concerns.

Like I said before, experimentation is paramount to get the best signal.

I am fine with the ground mount concept at least to start quick and simple.

Does anyone have an photo and or diagrams of a Talking House indoor style transmitter install running a ground mounted antenna outside?

If I put the Talking House in a garage, outbuilding, or similar and dig a trench to bury coax that goes to the antenna stack will this be compliant? I realize the TH indoor units have the outdoor connector port but totally unclear how to be compliant. I certainly can trench and wire anything (well versed there).