If I had to do it over again, instead of the Comet 95SL 5/8ths vertical, I'd run a Circular Polarized like this:
Run 30 watts into that, and it works better. Not sure about AM though. As I said, I'm done with FM. My SpitFire penetrates the buildings around me. When I finally get around to tuning the antenna, and finish building my SSTRAN, I'll really feel good about this again.
Doug
Thanks Legacy! I'm a member there now!
Doug
... Another downside to part 15 AM. The 1-2 mile ranges some can get is OUTSIDE only to a car radio! It wouldn't get you into the building accross the street ...
Maybe so for steel-reinforced high-rises and stucco buildings having metal meshes over their exterior walls.
But a legal Part 15 AM setup can generate a field of close to 5,000 µV/m at a horizontal distance of 50 meters (160+ feet) -- which distance probably would include buildings/homes across the street in many residential areas. (See the graphic below.)
As a reference point, each AM station I can receive here on my Tecsun PL-880 portable receiver displays the same relative signal strength both inside and just outside my house.
I can listen to WHO, Des Moines, IA during the daytime equally well just outside my house as inside my house, even though their groundwave field strength arriving at my house is about 100 µV/m.
Thanks to Rich and Radiodugger.
Mark
I was gunna say, I didn't think AM had any problems penetrating standard brick and morter wood beam constructed buildings. I've had the same results as Rich, with most signals being the same strength indoors. Only the weakest of weak AM stations seem to benifit from having the radio by the window, which is only a marginal improvement. The biggest thing is getting around all the noise emitting devices inside.
That's the real problem....it's the A/C power that has all the dirt emanating from it that you are surrounded by in your house. The real killer of AM inside. Some areas worse than others.
Mark
Based on feedback from neighbors and friends, I was surprised folks nearby listen on clock radios by their bed. They hear me when I sign on at 5 am! Down the street at pre-sunrise? WTF? I didn't think I got outside the window at night! Hmmm.
Maybe it's because of where the antenna is. I dunno, guys. I ain't done yet. This SpitFire keeps surprising me!
Doug
How are you finding out about all these listeners?
Wish I could know who's listening to me! If any.
I give out an email address on air but never have a response to it.
Mark
Only a dozen or so. Neighbors I've known for years.
Doug
There is only one way to find out if anyone listens, if email doesn't work, get a phone line for the station orrr just ask around. If you don't mind asking around.
Back when my family lived in London,Ky we were in a mobile home park.
I let management know what i was doing and assured them it was all legal, following the parks guidlines for antenna height wasn't too bad. 3 feet above the homes roof and no higher, no guy wires or towers allowed.
I used a mast pipe stapped to the guard rails of the front porch and a folded dipole on top of that mast. Covered nearly all of the park with a Ramsey FM 25 B set at it's lowest setting which is roughly 1.2 mW.
We ran that way for years, starting on 95.7 FM and eventually moving to 105.3 FM to avoid interference to a station that skipped into London from Louisville,Ky.
That station was Rock 95 Seven and then Rock 105 Three.
Lots of fun.
Barry of BBR 1620 AM
"Rather it limits the TOTAL length of the "antenna," "feedline," and "ground lead" connected together to 3 meters."
Which gives us several choices, for example:
Eliminate the need for a feed line by placing the transmitter close to the antenna system, split up the difference, 5 feet of antenna, 4 feet of ground lead.
All ground and a short stubby radiator...won't be effective beyond 100 feet give or take.
Mount transmitter and antenna close to the ground using all 3 meters for the antenna, bury ground elements and broadcast. Not including the coils in any of these setups because we know some type of matching network needs to be in place to effectivly use all the available flea power we can muster.
There is leaky cable transmission and of course carrier current.
Years ago, i had a Heathkit 35-in-1 Electronics Lab and one of the projects was an AM transmitter. I had a spool of speaker wire that dad brought home from work, it still had 200 feet of wire on the spool.
I ran a 10 foot piece of copper wire out the window to a ground rod below my window and 150 feet of wire from that spool out to a tree on the other end of our property.
With fresh batteries ( 4 D Cells) and a slight modifcation to the audio circuit, i was able to hear my station a mile out but the signal wasn't stable and modulation was probably only 70%. Still i had fun with it all the same. My audio source was an old tube type reel to reel made by webcor.
Barry of Blue Bucket Radio 1620
I tried a longer wire on my Radio Shack kit transmitter too, using this steel baling wire that my dad had, the cheap, thin stuff that hold up a drop ceiling or is wrapped around a broom to hold the straws in place, just farm wire from the feed store, and galvanized.
It was a whole bundle, and could have been 200 feet. I ran it from the transmitter in the basement, up several flights of steps, and through several rooms, but when I connected it the transmitter stopped broadcasting.
I ran it outside, strung through a line of bushes through the yard, but it still wouldn't transmit when connected, probably from the bare wire touching all kinds of things.
I did have success with connecting to window screens and the land line phone and other objects. The phone was great, got a few hundred feet, but with the supplied green wire I could barely get it upstairs across the house. True, my wifi doesn't reach that well in that case either, diagonally to another floor.
I had an XXX-in-1 project kit and its AM transmitter was micropower too, but there was a project in it called an "MCW Transmitter" that put out a screechy tone, and that thing was pretty powerful right there. I could hear that like 5 times as far, but it was still probably a few milliwatts.
I would have liked to have one of the Knight phono oscillators, I was power and range hungry, but was just starting to learn electronics. I wanted a real station and to be a DJ for my neighborhood, the place I ran around in and knew people, plus friends from school. A mile or two would have been great! We had fun with a few hundred feet though, good fun!
I've heard talk of 1 mile on the wire using the TH transmitter. Even with the home made ATU i twould not go that far. With the Spitfire its sounding promissing however.
I can imagine what at least 1 Watt would do on AM for those who need a stealth antenna.
The SpitFire is a great back up transmitter! But the SSTRAN AMT-3000 is the one ya want. A fifth grader could solder it together. The GAIN and MODULATION adjustments are a must too. The SpitFire has none of that. But once the Orban Studio Optimod is adjusted to the right level, the SpitFire SINGS...
Doug