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On 8/1/2014 12:22 PM, Rob wrote:
Jerry Stuckle wrote: On 8/1/2014 8:18 AM, Rob wrote: Jerry Stuckle wrote: On 7/30/2014 1:22 AM, Lostgallifreyan wrote: Jerry Stuckle wrote in news:lr9ohj$33f$1@dont- email.me: But the amplifier you're trying to use is meant to feed a receiver directly, not another antenna. So output is going to be very low (on the order of microwatts) - much lower than any amplifier which feeds an antenna. Small point, but.... Microwatts. Those new legal microstransmitters are said to be in NANOwatt range output, but allegedly work on the distance scales I'm interested in. Microwatts should certainly have worked, but despite the crude test dipole being good (on standard wired reception test anyway), it didn't work for transmitting even a foot or two with the radio's whip parallel to the upper part of it. If nanowatts should have, the MAR-6 looks like driving picowatts, if I'm lucky. ![]() I would suggest you check again. Receivers aren't that sensitive. Most unlicensed transmitters are in the 100-500 mw range, and have a coverage of maybe 100 feet. And picowatts aren't even worth discussing. You were the guy that believed that dBm meant dB over a millivolt, weren't you? And claimed that you had all that experience in cabling and signal levels? And thought that digital TV was transmitted at the same ERP as analog? I'm getting more and more astonished that you made any working system and did not just fry the expensive receivers of all your clients! And I'm more and more astonished that you seem to know my business better than I do. I certainly do! Your claims are all hogwash. Either you did not know your (technical) business when you were in it, or you have forgotten everything now that you are out of it for decades. No, you know NOTHING about my job, the people I employ or their technical expertise. You think EVERYONE IN THE WORLD is as smart as you are. But here's a clue - the VAST MAJORITY OF THE WORLD is SMARTER THAN YOU. You have no idea about what orders of magnitude are involved. For example: a picowatt is about 8.6uV in 75 ohms. An FM receiver will give a clear signal on that. Not full quieting, but certainly receivable. I know EXACTLY what a picowatt is. And I also know what portable receivers are capable of. Sure, if you feed a picowatt directly into the front end of a receiver, a good receiver will hear the signal. But what field strength do you need at the antenna for a portable FM receiver to hear that signal? And most of your inexpensive portable receivers will not hear much of a signal (if at all), even if you do feed a picowatt directly into the front end (not that you can without major surgery on the receiver). Unlicensed transmitters for dedicated frequencies like 433MHz (wireless headphones and the like) are about 10mW, and for broadcast bands (e.g. to link an MP3 player to a radio) they are even less. E.g. in the FM broadcast band the limit in the EU for such a transmitter is 50nW effective radiated power. That still allows for a 30dB path attennuation for a usable signal on the receiver. Sure, but you're also talking a 5Khz deviation (actually about 12Khz bandwidth). Commercial FM uses 75Khz deviation (typically around 180Khz bandwidth). A huge difference. But as you are used to jumbling up your dBm and dBmV values, you have no idea about that. Your business was probably connecting ready-made equipment, and selling. But certainly not testing and debugging, that is clear. No, i am not used to jumbling them up. You just have no idea what my industry uses for measurements. IOW, a typical troll - thinks he knows it all when he knows absolutely nothing. -- ================== Remove the "x" from my email address Jerry, AI0K ================== |
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