WEAK-AM

Part 15’ers– You may think this is off-topic, but it isn’t. If you are an avid AM radio listener, the time to act is NOW. If you are Part 15 AM operator, you MUST get involved in this issue!

Part 15’ers– You may think this is off-topic, but it isn’t. If you are an avid AM radio listener, the time to act is NOW. If you are Part 15 AM operator, you MUST get involved in this issue!

IBOC is a menace to AM radio! It is being forced on the American listening public by large broadcasting monopolies like Clear Channel. The NAB, the FCC and other key industry players have also been drinking the Ibiquity kool-aid.

An IBOC station occupies at least 3 AM channels, and if it’s local it will hog up to 5 or even 7 channels! And according to the FCC, this is “legal”! You will not be able to listen to the DX stations you enjoy at night, but in many cases even daytime listening in your own market will suffer. In my city, there are plenty of stations that are only spaced two channels apart. It is very fatiguing to listen to the shrill hiss, whine, and screech of IBOC sidebands, if you haven’t noticed. Not only that, but IBOC stations sound bad in their own right– they have their audio rolled off to less than 5 kHz, and you can never completely get rid of the hiss in the background!

Many frequencies at the high end of the band that are currently usable for Part 15 operation will disappear as high powered stations that are hundreds– or even thousands– of miles away pollute them, until they are just a sea of noise.

Please visit www.stopiboc.com to find out how you can help. One way is to write letters to IBOC stations and complain about interference to the stations you want to listen to. Or, just tell them that they sound bad! I just wrote a lengthy letter to the CE of a major market station. Most don’t care one bit about their listeners’ objections to IBOC. But don’t let that stop you from complaining! The more complaints, the better!

You can also complain to the FCC, though I don’t know that they will pay any attention. Other organizations to contact could include the NAB, New America Foundation, and Free Press (just do a Google search for these). With these latter organizations, you will want to explain the connection between large owners that are blocking reception of other stations through the use of their IBOC “jammers”.

Maybe you are thinking that perhaps in the future, Part 15 stations could go digital and use IBOC. Forget about it! First, it will be years before any equipment becomes available that you could afford, if ever. Second, you will not be able to pay Ibiquity the required royalties for the use of their patented CODEC. Can you believe that they have convinced the FCC to allow them to be the sole source of the technology that will eventually be used on every single radio station in this country. Isn’t that a sweet deal?! Yes, a few radio industry people are upset about that, but not enough to make a difference. And they are mostly small market stations that are not going to be able to afford to switch to IBOC, even if they would be happy with the 10 miles of coverage they MIGHT get.

So don’t just sit there! Get busy! Visit www.stopiboc.com now and learn how you can become involved. They also have some excellent audio files that you can listen to, if you’re not convinced yet!

Awhile back, there was a thread about field intensity meters for AM. Maybe this link is posted somewhere else here, but I haven’t noticed it. So if you are interested in making your own, check out this cool web site by David Forsman, WA7JHZ. You’ll need to scroll down the page a bit until you come to the “Test Equipment” section, where you’ll find the EMF Intensity Meter project– designed for use in the 0.54 to 1.70 MHz band! Also check out the other nifty projects, including a 160 meter AM QRP transmitter that could easily be modified for Part 15 use on the AM band.

Here’s the link: http://myweb.cableone.net/adamsmed2/catalog.htm

Hey folks! Cool tool alert!

Hey folks! Cool tool alert!

You will find this small app extremely useful for testing your LPAM transmitter and audio system. Visit http://www.realtraps.com/info.htm to download the Virtual Minirator, a very small PC application that will allow you to generate tones, sweeps, white noise and pink noise.

This is a straight executable– it doesn’t install anything on your PC. Just click the downloaded file to run. Follow the instructions that accompany it. The UI takes a little getting used to, but you’ll get the hang of it.

It’s winter here in the north, and therefore not a good time for outdoor antenna experiments. So I’ve got an idea for something to try until the thermometer rises to a more comfortable level.

It’s winter here in the north, and therefore not a good time for outdoor antenna experiments. So I’ve got an idea for something to try until the thermometer rises to a more comfortable level.

Indoor antennas are not known for great performance, but let’s see what you guys think of this idea. I have a space in the attic where I could install my SSTran. If I put the transmitter on the attic floor, I could ground it with a short wire 🙂 to one of the electrical conduit lines that distributes power to the rooms below. Potentially, I could even lay out some additional radial wires on the attic floor. The antenna wire could extend vertically about 6-7 feet (a compromise, I realize). It would be a relatively simple matter to add a top hat made of 6-8 ~1 meter long wires. The wires could be tacked to main cross beam and to the rafters. The ones along the cross beam would be horizontal, but the others would have to angle downward to accommodate the slope of the roof. I hope that that this would not significantly detract from the top hat’s performance.

It gets cold up there, but at least the transmitter is protected from the elements, and therefore would not require a special enclosure. Adjustments would also be easy to make, and it would be easy to run power and audio to the unit.

Has anyone tried something like this, and if so, how did it work out for you?

Now that I’m happy with the audio performance of my SSTran, I’m going to start working on modifications in earnest! NOTE: None of these modifications will affect the input power to the final stage!

Now that I’m happy with the audio performance of my SSTran, I’m going to start working on modifications in earnest! NOTE: None of these modifications will affect the input power to the final stage!

In the works:

1. Frequency adjust trimmer to allow the carrier frequency to be set precisely on channel.

2. Improved output match efficiency using a large iron-core toroid instead of the small axial-lead inductors. I just ordered up some #15 material toriods from Amidon Associates. The toroid should still fit inside the enclosure.

Planned:

1. On/Off switch

2. Remote metering for the output

3. External access to the output trimmer capacitor

4. Reduced adjustment range for the Compression pot to limit it to 1:1 – 2:1 and make it easier to choose low compression ratios

5. Negative peak LED to indicate when the carrier is being modulated at -95% or greater

I’ll let you know how it turns out!

Meanwhile, I have to say that I don’t agree that Part 15 AM can’t be used for high fidelity transmission. My SSTran sounds great on classical music now, and so does my Rangemaster. Listening on a high quality AM radio is an amazing experience! The SSTran signal is plenty strong enough to give excellent reception anywhere on my property, and the Rangemaster pushes that out to a couple of blocks. Sure, as you get further away, the audio quality drops due to noise, co-channel interference, etc. but it still sounds good and these impairments do not really spoil the enjoyment of the music until the signal gets very weak.

I have been a longtime devoted listener to classical music on AM over CBC Radio One (until they took it off the air last year) from CBL-Toronto (now off the air) and CBW-Winnipeg. AM radio is very usable for classical music, especially if you’re actually interested in the music and not just listening to the equipment. There’s a commercial classical AM station in Kansas City, KXTR (1660) that I hear from time to time. So it definitely can be done!

Part 15 is, in fact, a great place to experiment with high quality AM because we aren’t forced into a need to over-process the signal in an attempt to be louder than everyone else on the dial. Don’t get me wrong, though– some processing is good, and if someone offered me a used Inovonics 222 at a good price, I would probably be inclined to pick it up!

Question withdrawn.