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This looks like a developing story, great photos, too…

This looks like a developing story, great photos, too…

East Lawton Community Radio reports, via their web site, that:

“The AM transmitter antenna equipment has arrived! The construction detail and workmanship is outstanding! Excellent work Carl! (the antenna guy).”

Here’s a teaser photo, linked from the ELCR web page:

Be sure to visit the East Lawton Community Radio web page at http://www.geocities.com/ab5ui/ELCR.html

ELCR says to be sure to chek back often, as more info will be posted soon – Drool 🙂

I have seen quite a few programs mentioned on Part15.US for broadcast radio automation software…

I have seen quite a few programs mentioned on Part15.US for broadcast radio automation software…

but all that I can remember have been for DOS or some version of Windows. I have finally found a program for those hardy souls who run Linux.

Rivendell is FREE automation software developed for broadcasters by broadcasters. According to the Web site, “Rivendell aims to be a complete radio broadcast automation solution, with the facilities for the acquisition, management, scheduling and playout of audio content.”

More details are available on the Rivendell page of the Salem Radio Labs Web site:

http://www.salemradiolabs.com/rivendell/

Version 0.9.48 of Rivendell was released on Monday, August 8th, 2005. The release announcement is at:

http://lwn.net/Articles/146667/

(Don’t be put off by the version number. Most Linux software starts off as a 0.1 or even 0.01 version, and is quite polished long before the magic 1.0 release.)

From time to time, a visitor will ask how to choose the right transmitter for a successful Part 15 AM BCB operation…

From time to time, a visitor will ask how to choose the right transmitter for a successful Part 15 AM BCB operation…

Since each operator will have different needs, interests, skills, budgets and content goals, I really don’t know if there is an ultimate answer. What follows is a general approach, and shared here for comments and suggestions.

I’d say there’s four areas to look at, power use, modulation, audio processing and RF buffering.

Power Use

Many folks use the power input limit criteria for compliance – that’s the 100mW standard that’s frequently kicked around.

That means you get 100 mW of power DC input into your XMTR, and it’s up to your XMTR to get the very most RF out of the 100mW DC in.

Good oscillator and buffer designs help this outcome a great deal, so you’ll want to find XMTR designs that get the most RF out of the power that’s dribbled in.

PLL or XTAL seems to work best for AM BCB, VCOs have never really made me too happy when you’re shooting for 24/7-365

So job #1 is getting the most carrier out of 100mW DC input. Some XMTRs are more effective at squeezing out every drop.

Modulation

Grabbing your audio input and effectively modulating your carrier is the next job your XMTR needs to do well. Some XMTR designs will be better at this than others, and the effectiveness of the modulation of the carrier will have a big impact on how happy you are with your station.

A short example – I had a PanAxis AM100, and I was very unhappy because it seemed to have a very short range. I contacted PanAxis and they gave me some modulation adjustment tips. I made the adjustments, and all of a sudden I could hear my XMTR a mile out. It seems the radio waves were actually going quite a distance, but the carrier wasn’t modulated well enough for my radio receiver to reproduce any audio – I was getting out, I just couldn’t hear me!

Adjustments aside, some XMTRs modulate better than others, and some modulation stages can swallow higher audio outputs – that makes your range seem greater because you can “kick over” the detector in receivers that are farther away.

Audio processing

The audio modulates better if it’s conditioned before it’s modulated.
First, the audio should be a fairly high voltage signal. I use an LM 386 low power audio amp IC in front of my XMTR, and it helps boost the audio from my PC sound card.

Next, the audio should be compressed. It helps make the station sound more like the other stations by keeping low volume content from dropping out because the amplitude isn’t adequate to modulate the carrier.

Finally, it should be limited so that certain loud content doesn’t swamp the modulation section and make that icky “it’s turned up too much” sound.

Some XMTRs do all of this internally. Some do none of it. Some do some. What you choose depends on what processing equip you might already have, the bandwidth and average VU level of your content, how much DC power your going to want to pump into the XMTR (All that processing needs addidtional input power), what your personal tastes might be and so on.

RF Buffering

The final stage of the XMTR should buffer the RF output adequately, so that minor changes in the environment around your ANT don’t negatively impact your oscillator and ruin the ANT/XMTR match, etc. Anyone who has fiddled with an unbuffered XMTR will know what I mean – it’s as bad as a VCO.

Here are some transmitter review sites that cover these issues. Always remember that “Net” means Not Entirely True, and draw your own conclusions!

http://www.vintage-radio.com/reviews

www.toddjenkins.com

http://www.geocities.com/raiu_harrison (old, but good)

www.oldtimeradioprograms.com

Previous blogspot article

http://www.part15.us/article

Our reviews

http://www.part15.us/modules.php?name=Reviews

FM modulators for iPods are becoming very popular…

FM modulators for iPods are becoming very popular…

Almost as popular? Modifying an iPod mod, photographing your handy work, and posting a “how-to” web page.

Is it Part 15 after you hack it? That’s probably out the door as soon as you crack the case. The only sure answer is that you’ve smoked your warranty!

With that stern disclaimer in in mind, please to be enjoying the carnage below…

Start here, about halfway down the page:

doc.weblogs.com Overview

Then read these:

www.jiggybyte.com Mods

mypage.iu.edu Mods

www.xmfan.com Mods

www.geek.com Mods

www.broadbandreports.com Mods

www.mediageek.org Mods

And here’s some oldies but goodies

www.i-hacked.com More guts

www.ee.washington.edu Husky electronics

members.tripod.com Mycal memories

Send us your frankenpodmod link up! Use Feedback

Carl Van Orden, antenna guy writes “It is no surprise that FM part 15 broadcasting creates more interest than AM part 15 broadcasting…”

Carl Van Orden, antenna guy writes “It is no surprise that FM part 15 broadcasting creates more interest than AM part 15 broadcasting…”

I guess that if I were not acquainted with broadcasting at all I’d want to be on the FM band, provided I wished to supply a broadcast service.

With both AM and FM part 15, you can broadcast very easily about 200 feet. The difference between the two bands is that with FM, you can only broadcast about 200 feet legally; that is the FCC limit in range.

All part 15 AM transmitters will achieve that range with a simple wire antenna and without any kind of ground system. Since I build AM part 15 antennas, I get more emails that ask questions than I get actual orders, but that is ok.

The main question I get is about range: “how far can I broadcast?” With a SStran transmitter and one of my coil-loaded antennas we can guarantee 1 mile at least, but there are things you can do to improve that range, all 100% legal!

Remember, AM (to most people’s surprise) is basically a ground based medium, meaning most of your listenable signal will be heard via a ground wave.

Based on your particular soil conductivity, and the availability of a clear frequency at the high end of the band, you may immediately see a better signal than 1 mile, albeit perhaps not clear.

Using a transmitter kit like the SStran, and my antenna with a properly installed ground system, I’ve had reports of up to an amazing 4 mile radius of range! Even in the poorest conductivity areas, I’ve had reports of solid, 2-mile signals!

For my money, I’d rather have a superior strong signal in a 1-mile contour than a poor signal over a 3-mile radius. As the FM band continues to clog, the AM band actually continues to open up, and with the onset of HD AM radio, surely more channels will open up in the future.

The key to being successful in part 15 AM broadcasting is to provide programming that no one else is doing. If you can do that, you can not only provide a great community radio station, but maybe even make a little money using your station as your own “on the side” business.

Don’t forget, your community has people providing lawn-mowing services, there is garage sales, perhaps you close to a church that would like to broadcast their services, there are baby-sitting services too.

Do you live in a community whose people are mostly retired? Or an apartment building with more retirees than working people? Perhaps a big band format (instead of the rock and roll you prefer) could be an option!

Again, the key is to find an open frequency, or as clear of one as you can, build your ideas of format for the people you live close to, and cater to them.

As an antenna builder, I’ve been thinking of offering part 15 antennas, but the truth is that overall, I feel most people are not satisfied by the range of the FM transmitters you are allowed to use. On even a stereo system, some of the best AM kits sound FM like, and strong, and you will have range if that is what you want.

The most important thing is that we get more part 15ers on the air, to promote community radio, to provide for potential listeners, and to do it in an economical way.

Carl Van Orden,

antenna guy

[email protected]

One of the best radio blogs going was written up recently…

One of the best radio blogs going was written up recently…

The June issue of Monitoring Times Magazine carried a very complimentary write up of the most excellent radio blog futureofradio.typepad.com. The article, appearing in George Zeller’s Outer Limits column, calls webmaster Harry Helms’ futureofradio.typepad.com “thougt provoking, and well worth a visit.”

If you didn’t catch the article, be sure to visit the site!