| Author | Message | ||
     brian Unregistered guest |
hi i am planning on building the transmitter , the one that works with your pc. i was planning on using it to communicate with my friend a few miles (2-3 miles) down the road and was wondering if your model had the range, and if not how to achieve this range. | ||
| Simon Quellen Field (sfield) Senior Member Username: sfield Post Number: 323 Registered: 12-2004 |
If you have an Amateur Radio license and a good receiver, an oscillator at 28.8 Mhz into a good antenna will go around the world. | ||
| MadScientist (madscientist) Junior Member Username: madscientist Post Number: 10 Registered: 4-2005 |
Hell, If you have the right antenna, a linear is not all that far fetched, and is legal in some locations, that would more than do this... Sorry Simon, Im a science fanatic (not saying youre not hehe) and this just happens to be right up my alley.. I bought a transmitter module recently, albeit FM, that is capable of 1/4 mile right out of the box... tweak it and its capable of well over a mile. In the process of learning what I could and couldnt do, I found a site, that is mostly devoted to what youre thinking. http://www.part15.us has massive amounts of information that will tell you what you can and cant do in the AM band... Some of the transmitters built are legally transmitting more than 5 miles... just keep an eye out, the FCC doesnt play around. Your range will depend on what frequency you plan to operate at, as well as how much power you will use and how long your antenna is... The ones described on this site are very low power and would require boosting that potentially puts them outside the legal range. Do your homework first! Having the FCC and their associated droids banging on your door cant be a good thing, I have heard stories of as much as $10,000 per transmission, PER OFFENSE! It is wise to make sure youre not interfering with anything before you do something like this! Steve | ||
| Simon Quellen Field (sfield) Senior Member Username: sfield Post Number: 331 Registered: 12-2004 |
Don't use a linear amplifier with the AM transmitter I designed for the web page. My design was optimized for simplicity, and has no filtering on the output to prevent spurious emissions on harmonic frequencies. An AM transmitter that can legally transmit 5 miles under the U.S. Part 15 regulations would need good filtering. I have been having fun building radio transmitters for the last 40 years (I hold an Amateur Extra class license). But if everyone started jamming the amateur bands with splatter from amplified unfiltered oscillators, my hobby would lose a lot of its appeal. ;-) | ||
| MadScientist (madscientist) Member Username: madscientist Post Number: 20 Registered: 4-2005 |
That was pretty much my point, I didnt mean to strike a nerve hehe, I was thinking more along the lines of the simple 2 transistor designs than anything even approaching, say, a 1000W module (or anything even remotely approaching). I was thinking more along the lines of 100mW. Granted, even the device as I was contemplating could definitely cause problems (Im assuming that the output from the osc module is square), and would cause unacceptable harmonics. I was essentially ranting, throwing ideas around...  On that note, I stand corrected, and no, it would not be acceptable to run anything like this for any length of time, but would prove the concept. |
