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"Harris" wrote in
. net: Thanks very much for the lengthy response. I see that I have much to learn about scanners and antennas. Regards. How are you determining what the signal strengths are? (I'm talking about actual rf signal levels at the input to the scanner, NOT what you're seeing on an "S" meter or hearing from the speaker.) If your outdoor antenna were delivering more signal strenghth to your scanner, your intermod would get worse, not better. As I tried to explain, when the scanner is subjected to STRONG local (unwanted) signals, the scanner will be de-sensitized. This will make it difficult to hear weaker signals. If attenuation is placed between the antenna and scanner, this "de-sensitization" effect will be reduced, and weak signals will actually appear stronger. In other words, less signal strength may actually improve reception in your case. Often folks try using pre-amps to improve reception, only to find that the preamp degrades reception (especially with handhelds). This is similar to what I described above. Sometimes, less is more! There you go. Adding attenuation improved your reception. I'm speculating that the attenuation (loss) in your feedline is having the same effect. RG-6 is much better than RG-58. However, 85 feet is a pretty long run. All coax cables have higher loss as you go higher in frequency. If your overload/intermod problems are indeed caused by nearby cell sites, those 800 MHz signals will be attenuated more than signals at lower frequencies. And your outdoor antenna is probably less effective at 800 Mhz than at lower frequencies. So your antenna and feedline are acting like a "low-pass" filter in that they attenuate the higher frequencies. All of that is consistent with what you are hearing. Art N2AH |
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