WEAK-AM

Isn’t that one of the first questions we always ask when we go on the air? Well recently I purchased a Hamilton Rangemaster to add to my stable of transmitters (which includes the SSTran, the Ramsey AM25C, the Vectronics AM-1, and the venerable Knight Wireless Broadcaster). Of course, I was excited to find out how far it would go. And, I’ve developed an interesting technique for DXing that I want to share with you.

But first, the Rangemaster is awesome! I like it very much. I also like my SSTRan very much (but for somewhat different reasons). I bought the Rangemaster because I wanted to be able to operate it withough worrying about complaints about unlicensed operation.

So what did I find? Well, first of all, a little background. I am operating on a cluttered frequency (aren’t they all?) in a major metropolitan area, from out in the suburbs. I don’t have an ideal site. I have a small yard with a lot of trees. I wish I lived on a farm with hundreds of acres to put up experimental antennas… alas, that is not the case. Temporarily, I’m just using the CB whip antenna. The transmitter is grounded to a single 6′ ground rod. I’m watering the ground rod with a garden hose at a slow trickle. I plan to add additional ground rods over time.

When I first put the Rangemaster on the air, I didn’t pay close enough attention to the power adjustment instructions, and the range was very poor. Then I re-read the instructions and brought the power up to 100 mW, and the range improved markedly. I don’t own a field strength meter (I wish I had bought that Potomac FIM-41 I wanted when I was a kid)… So here is what I can tell you… my signal is really strong for about 200-300 feet, such that you can comfortably listen to it in a neighbor’s house on a reasonably good quality portable radio with little noise in the background. In my neighborhood, that’s about 2-3 houses away. The signal is intelligible for about .25 mile (2 blocks). At night, when the QRM is bad, you can just about listen to it a block away.

Now for the interesting part. I decided to see how far it was really going… despite the QRM. So I used the tone oscillator on my Shure M267 mixer, which is driving the transmitter, to generate a 1 kHz tone. Now, that tone is REALLY annoying to listen to at close range, but as the signal starts to get weak, it’s not as bad. You will find, if you try this, that the tone will stand out even if your signal is buried under 3 or 4 other stations in the muck, and you will be able to hear it for a long way. The ear is very sensitive in the 1 kHz range. So I put on the tone and drove off to work. In the morning, local sunrise is around 7 a.m. and it didn’t go far… about a mile was the farthest that I could hear it. But on the way home around 4:30, I was shocked to discover that as I was about 2 miles from my home, I started to hear it! And today, after I made some improvements to the ground system, I actually heard it several miles away. But the useful “broadcasting” range remains only a couple of blocks at most.

Now, what conclusions can be drawn about this? First, don’t try this experiment unless you are not afraid to be noticed. A 1 kHz tone on the AM dial left on all day stands out like a sore thumb. (So maybe don’t leave it on all day like I did). Second, the useful range of a Part 15 transmitter is a LOT less than the distance it actually can be be detected. On an area basis, if two blocks is equal to 1/4 mile, then the useful coverage area of my station is very roughly 0.2 square miles. But the absolute limit of reception is considerably farther. Now I will say, if you wanted to key the tone with Morse code, you could probably communicate at some distance… (yes, I am a ham radio operator). But that’s not why we get into LPAM, is it?

I noticed some interesting things while driving around. As you drive away, the signal rapidly drops off to a low level, such that you would think it would fade out entirely… but it “hangs in there” for a long, long distance (with occasional fade-outs). It’s amazing to me that after the signal gets weak, I can drive quite a bit farther before it actually disappears.

In any case, I would be interested to hear from people that try this experiment. How far can YOU go?!

I found the review I was looking for. It was about an LPB transmitter that some say was made by Hamilton.

I will be writing about my own experiences with the Rangemaster here soon.

WEAK-AM

I found the review I was looking for. It was about an LPB transmitter that some say was made by Hamilton.

I will be writing about my own experiences with the Rangemaster here soon.

WEAK-AM
Classical Music and More!

I’m starting a tribute site for the former KSIR 1470 AM– a great small town station I did some work for in the 1970’s and 1980’s. If you worked there or have anything to contribute, I’d love to hear from you. Here’s the web site: www.ksir1470.com

WEAK-AM
Classical Music and More!

OK, I got all excited about jingle packages after visiting the “Keener 13” web site– and finding the nice productions from PAMS and JAM.

OK, I got all excited about jingle packages after visiting the “Keener 13” web site– and finding the nice productions from PAMS and JAM.

I hate to bother them any more than necessary, so has anybody here worked with them and do you know if their “personal use” policy includes Part 15 radio?

They say “no broadcast” of “personal use” jingles, but the FCC doesn’t consider Part 15 operation to be “broadcasting” (otherwise, you’d need a license, eh?)

Oh– you don’t know what a “boobam” is? Just Google it, or visit jingles.com!

WEAK-AM
Classical music and more!

OK, here’s my problem… I bought a couple of sections of aluminum tubing from Texas Towers to make a new antenna from… the idea being to use this with the base mounting section of a re-purposed Hustler 4BTV vertical.

The two tubing sections are designed to fit together, so I slipped one inside of the other a short distance to assess how well. The problem came when I tried to separate them again… no deal! For the life of me, I cannot get the tubing apart now!

And now I have discovered that “a short distance” means about a foot!. So if I saw off this area, I will lose about two feet altogether from the available length. Not good!

Any ideas on how to get stuck aluminum tubing sections apart?

I escaped to the lake house for a few days. Of course, my SSTRAN and computer came along! Nice thing about being out in the country is that there are quite a few more clean frequencies– at least in the daytime. But I didn’t have time to set up an outdoor antenna.

So I tried the floppy 10′ wire tacked to the wall on my wooden screened porch. The signal was reasonably OK inside the house and a little way into the yard, but faded badly at the end of the dock about 100 feet away. That was one of the places I wanted to listen, so I decided I needed something better.

A trip into town to Radio Shack netted a 100′ spool of 22 gauge 2-conductor speaker wire. I had the idea of making a “T” antenna out of this. It’s a lot like an FM dipole, except here we’re going to drive the two conductors together. Thus, I connnected both wires to the antenna plug and tacked them vertically to the wall for a distance of about 6 feet above the transmitter, which sits on a tabletop. At the ceiling, I pulled the conductors apart and ran them in opposite directions along the wall to create the “T”. This is in effect a “large-ish” top hat for a very short vertical monopole. In my case, the two horizontal sections are each 20′ long. The final step was to tie all of the ham radio antenna cables together and use those as a ground.

The results were pretty satisfying. I didn’t have to make any modifications to the transmitter because there was still enough tuning range to accommodate the T antenna, and it tuned easily. Inside the house, the signal is now extremely strong. Outside, it covers my yard very well, and is quite good at the end of the dock. In fact, it goes about another 100′ out into the lake and covers my two adjacent neighbors’ homes as well.

Of course I had to do some drive-around tests to see how far it would go. Under absolutely perfect noise-free conditions, I could hear the signal to a fair degree out to about .2 mile. I could even detect its presence here and there much further– perhaps 1/2 mile. I think that’s pretty good for an indoor antenna. The ground conductivity in this area is probably pretty low. The soil composition is primarily sand.

Setting up an effective indoor AM antenna poses unique challenges. I have another idea that I want to try involving the use of one of those spring-loaded metal poles that are intended to support plants, etc. I think I might try that with the transmitter sitting on the floor right next to it, with a loading coil in series. Finding a good ground is still a challenge. I have used cold water pipes, heating ducts, and electrical conduit with mixed results. Still, some sort of ground is naturally better than no ground!