Quote:
Originally Posted by Beaconhunter
I have thought about using external attenuators, but have some doubts about how this would work. If the attenuator is effective in blocking out the strong signals generated by the nearby cell towers, won't it also block out the much weaker 800 Mhz radio signal, since they are fairly close in frequency?
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Well as we've discovered, GRE radios are already artificially sensitive - at least to my experience on 800mhz. So much so that when trunking edacs on my GRE / Pro-164, it is only when the attenuator is inline that my confirmed weak trunking systems are truly just as weak on other radios like Unidens, Icoms, etc. So running with the attenuator is what I think should be considered the norm as compared to most other radios. Now add additional problems like a high-rf environment, and perhaps yet another 10db or so should be added by some other means. In other words, starting out with 20db of attenuation should be thought of as getting back to a real world "0db attenuation"
The real fix is to get GRE to tame that front end, but it may be a marketing decision to run this way really hot. Great for the sticks with the oem duck, but not so great for those of us in the rf-jungle.
(Note that I am frustrated by the fact that my conventional 800mhz channels that are just mind-blowingly strong without the attenuator are not affected so much at all by similar desense/overload! I wonder if you have any conventional systems that you could compare the problem with the trunking systems. At least on my 164, the scanner seems to have differing levels of rf amplification depending on whether I'm trunking or doing conventional - argghh.)
What could be complicating the issue are the power-cord and audio-cable antennas just dumping a lot of common-mode rf back into the decks. Since it seems to also affect your older Unidens, maybe try a test running without any audio cabling, or perhaps running with a dc-pack NOT connected to the vehicle to see if this changes the intensity for better or worse.