Range Limit for Legal Part 15 AM

[dbdigital]

Seems to me that either on this board or another, some creative person suggested the idea of attaching several transmitters to one antenna for greater output. I'm fairly sure the TXs would have to be synchronized somehow; but does anyone recall what the verdict was on that idea?

The feasability and legality of it? Just curious.

db

I've read somewhere in the FCC rules that you can build 5 homebrew transmitters... I was wondering if you could stack 5 transmitters and antennas, each one being 100 milliwatts and 3 meters, for an effective equivalent of 500 milliwatts and 15 meters?

like this diagram's example:



ok, how do you embed an image? It's 539x563 pixels, 15k.

And, what about the idea of stacking multiple antennas end to end so they act as one larger antenna?

Stacked, syncronized, part 15 transmitters work even better when the transmitters are mounted at the top of each antenna, and none is mounted at ground level.

What about the issue of the signal feeding back into the amplifiers as R. Fry mentioned? Is there a method that would prevent or minimize that?

db

 

[SUPERCASTER]

Seems to me that either on this board or another, some creative person suggested the idea of attaching several transmitters to one antenna for greater output. I'm fairly sure the TXs would have to be synchronized somehow; but does anyone recall what the verdict was on that idea?

The feasability and legality of it? Just curious.

db

I've read somewhere in the FCC rules that you can build 5 homebrew transmitters... I was wondering if you could stack 5 transmitters and antennas, each one being 100 milliwatts and 3 meters, for an effective equivalent of 500 milliwatts and 15 meters?

like this diagram's example:



ok, how do you embed an image? It's 539x563 pixels, 15k.

And, what about the idea of stacking multiple antennas end to end so they act as one larger antenna?

Stacked, syncronized, part 15 transmitters work even better when the transmitters are mounted at the top of each antenna, and none is mounted at ground level.

What about the issue of the signal feeding back into the amplifiers as R. Fry mentioned? Is there a method that would prevent or minimize that?

db

Close proximity directional antenna systems, segmented verticle monopoles, and synchronized transmitters have sucessfuly been in use for well over half a century. Properly engineered, multiple powered antennas in close proximity are no problem.