Weak After Week

"Intending to keep the transmitter indoors I use a metal window frame as part of a 6-foot vertical antenna that is finished off at the bottom and top by wire to approximate a 10' vertical, all phased to an external wall."

This could be some of the problem as the window frame could be upsetting the way the antenna works for the worse not the better. But you have exactly what you want your range to be.

From my frequency experience

From my experiences it's not unusual to have that kind of field strength nearby and then have it drop off quickly.

I had that effect on my Radio Shack AM Broadcaster kit that got me started, and I hooked a phonograph to it. Nearby it sounded like I had a megawatt, louder and wider than any other station. I thought somehow I'd created a high power signal by a wiring mistake, and I was worried about the kind of power it was putting out, that I'd jam neighboring radios and the police would come.

I found that the signal was already weak just outside of the house, and might have been gone in 60 feet, if that far. It's about the near field and concentration of signal indoors, caused by surrounding metal I think, and it happens with indoor transmitters like the Talking House too.

One thing you could try Carl is to connect a long radial to the ground side of the transmitter and lay it on the earth all the way to the other side of your yard, to give a kind of controlled signal. I've had strong signals along a radial before, not trying for that effect, but it happened.

I'd try it both with the I-beam connected also, and by itself as a ground and see which has the signal you want.

Boomer

Yes, I may have read that you had done some radial experimenting before, and it made a directional system.

The radial doesn't really put out much far-field signal because it's on the ground, but nearby to it the signal could be strong, and it might help the Wintenna radiate a little better.

There's an parallel in the way that drive-in movie theaters have been set up for AM carrier current, where the transmitter's hot side feeds the underground wiring that goes to the speaker poles. That way there's a strong signal near every car.

In the diagram I saw, I think the ground on the transmitter went to a ground rod near the projection building, but I wonder if an opposite branch of the speaker wiring could be used for the ground, kind of like a dipole underground.

Good to be doing this project, you have to give your kestrels and jackdaws something to listen to back there!

Boomer

Mark Hits the Mark

A true statement: "I still think that your "wintenna" is not the way the antenna was designed to be set up and it is adversly affecting your tuning to peak with the output of the transmitter."

I know you are right about this, Mark.

Several years back when I first tried this "Wintenna" design, the inventor of the AMT3000/5000 transmitters informed us that because the metal window frame is mounted as part of the building wall, it has an extremely different capacitance than a vertical antenna located in open space, and it is that added capacitance that makes it less able to tune correctly.

We found that it is possible to achieve a match by adding a capacitor in line with the transmission line, in the case of the AMT5000 a 23pF cap, but there is no way to achieve the much greater range possible from a clear and open location.

Experiences Planned and Unplanned

TheLegacy, I agree with you that some interesting things can be done with AM antennas up on rooftops or mounted high on a pole, but my particular plans are confined... in this thread at least... to optimizing the Wintenna, because it is the only known compromise for building an antenna that is both inward and outward facing at the same time, with the added advantage of keeping the transmitter safely indoors.\

The clumsy part of the Wintenna is caused because it is on an outside wall, with physical earth out beyond the building suitable for laying radials, but open basement underneath the floor on the inward side which, even though there are "ground-points:" such as I-beams, pipes, electrical service ground, it is not physically "under"ground and thus it becomes a maze of warped and distorted unintended dipoles adding peculiar phase angles and impedances. The solution would be to fill the basement with truckloads of dirt.

Therefore I plan to study the wild field of "artificial grounds", of the type HAMs devise for transmitter setups located indoors on upper stories of buildings with no access to earth ground.

Keep the ideas coming. We are only beginning.

I'd test with a radial out to where you want your signal, connected to the transmitter's ground. I've done it with speaker wire on a spool to make temporary radials, and rolled it up when done, and if it's not outside for too many days, there's no damage to the wire.

Thinking about how this works, I wonder about a power line enhancement I've had on my Talking House.. There are some setups I've done where there's been a strong carrier current effect, where the over-the-air signal will seem to go a few hundred feet away from my house, but I can walk to a power pole a quarter mile away and get a good signal with a portable radio held up to the pole.

That's with the transmitter and antenna fully indoors, and in the basement, and my idea had been that the antenna was radiating a signal into the power lines that was taking the form of a carrier current, but now I wonder if it wasn't the ground side of the transmitter causing it. Sometimes I've connected a ground wire from the TH's chassis to the ground screw on the AC socket.

Right Artisan, it would be better not to over-sell the capabilities of transmitters when it comes to range. It seems like people with an interest in selling them will do that, and I think in the community of users it amounts to boasting about one's coverage.

Then there are new people who fall into Part-15 radio and want to know the territory they can expect to cover, before they invest in a system.

Boomer

Boomer said "Then there are new people who fall into Part-15 radio and want to know the territory they can expect to cover, before they invest in a system."

I'd say that that is the most common question to those looking at Part 15 broadcasting systems. How much range will I get?

The correct answer, of course, is ... it depends. It depends on a number of factors that you can't control, such as ground conductivity, RF noise, surrounding geography and construction, etc. It also depends on factors that you can control, such as transmitter field strength, antenna location, audio processing, receiver sensitivity, etc.

But to say or to even imply that you'll routinely get 2.5 miles range with a legal Part 15 AM transmitter is doing that inquiring individual a disservice.

Maybe, just maybe, with a great radio, a near perfect installation and location, excellent ground conductivity, radials, the perfect geography and in just the right direction, you might pick a signal up at the 2.5 mile range. Maybe. Certainly not typically.

My experience has been that range will vary wildly with those factors that you can't control, period. Unless you're willing to move, you're stuck. On Bowen Island (basically just a rock sticking out of the ocean), I got 1/4 to 1/2 mile with my Rangemaster. In Pitt Meadows, on a flood plain with great ground conductivity, I managed well over a mile (and in just the right location, up to 2 miles). Same transmitter, same receiver, similar installations, but very different results.

And in fact, I managed to get close to a mile with a Talking Sign (similar to the Talking House) in Pitt Meadows, running the wire antenna outside. The Rangemaster had a better signal, with more range, but not that much better. Certainly not the difference that I saw between Bowen & Pitt Meadows with the same transmitter. I suspect that in that particular location (Pitt Meadows), I'd get close to a mile range with any decent Part 15 legal outdoor installation, due to those factors that you just don't control.

That's why I generally recommend that before anyone spend huge amounts of money, they experiment. Get an inexpensive transmitter such as the Talking House, put it outdoors and see first hand, practically, what kind of range you're going to get. You'll likely be able to better it somewhat with more expensive transmitters, radials, etc., but only to a degree. If all you can get is 1/4 mile, then don't expect to buy a Rangemaster and magically get over a mile.