This past weekend I installed one of the Hamilton Rangemaster AM1000 transmitters on the roof of my house. The installation meets the requirements for power, antenna, and ground lead length making it a legal unlicensed station per the Part 15.219 rules.
I have good news and bad news.
The bad news first – nighttime coverage in unimpressive. After just a couple of blocks there is noticeable interference from distant stations on 1700 khz. This was not a total surprise however, I expected XEPE “San Diego” (actually Northern Mexico) to give me some trouble. And of course, the noise floor is pretty high in spots around here.
The worst noise problems are near overhead MUNI wires and near businesses. These noise problems are prevalent day and night.
The good news: Daytime coverage is considerably better.
I did an afternoon “range check” walk around the neighborhood with a portable radio. For those keeping score, it was a Grundig Yacht Boy 400. This isn’t most sensitive radio in the AM band but it’s OK. Most car radios are better in the AM broadcast band. Shown below is the “coverage area”.
I put it in quotes because it is possible to pick up the signal outside these boundaries. The marked area shows where the station could be heard with comfortable listening. In some spots you’d have to re-orient the radio for best reception but the signal was not hard to hear.
The area covered by the daytime pattern is approximately 0.2 square miles. That doesn’t sound like much, but given the population density of the Richmond District, this coverage represents a potential audience of about 5600 of my closest neighbors. Not too shabby!
I think I could achieve better coverage with a better ground. The short ground lead connects to the steel pipe the AM1000 is mounted on. However, I don’t know if there is electrical continuity with earth. And even if it did connect to “earth” the soil around these parts is basically just sand. It’s not the good conductive soil that makes AM radio signals sing.
My first goal is full weekend, daytime programming. I’ll publish a schedule when I can reliably meet that programming threshold.