Well here is the final results of what I have done this morning, and listening to the aircraft band, I have not heard anything come back as of yet. I reduced the duplexers to 4 cans rather than 6, with 140 watts into the duplexer, I am getting 105 watts back out the antenna port. No decense that I can detect. Receiver sensitivity is right on track at .15uv @ 12dB sinad with the preamp installed. The audio out of the repeater is clean at this point. I spent almost 20 minutes on the repeater and nothing has gone wrong with it yet. I did find a few loose connections between the duplexers and the receiver, nothing in the transmit side, and not so loose they were ready to fall off, but not as tight as they should have been. I'm going to have some users work the system here this afternoon and travel about and see if I can hear it anywhere away from the repeater site.
It very well could have been a bad connection all along. I'm hoping this is the case and it won't creap back up on me.
Mathew
Dave VanHorn <[EMAIL PROTECTED]> wrote:
At 10:45 AM 7/8/2005, Mathew Quaife wrote:
>Typically to say, there is nothing in this area as far as repeaters,
>a few on 460 Mhz and one on VHF at 158 Mhz, other than the two cell
>towers more than 5 miles away, that is about it.
This gets into an area that I need to understand better, "how do you
know when it's "good enough"?"
How sensitive does a repeater receiver need to be?
How much isolation do I really need?
How much power should I be running?
All of the above, relative to an antenna, feedline length, mounting
height, and terrain..
Around here, terrain means basically flat, and sites at 100-200' typically.
Radio mobile is good at plotting coverage maps, but then you get into
what's the actual receiver like?
An HT has a pretty lame receiver, lame antenna, and puny transmitter,
but I haven't really looked at those numbers to see if they are all
proportional.
IOW, is the typical HT equally sad on receive, as transmit?
What about a mobile rig?
There's no sense in being an alligator, or a fruit bat, or spending
power and money in cans you don't actually need.
In the can side, I think the answer is, as long as you aren't getting
desense, you've got enough isolation.
You might add cans to get around a particular interference problem,
like a nearby transmitter or receiver that is out of band, but still
causing problems.
At one site, we used to have a 1kW VHF paging transmitter about a
mile away, that put a very nice signal into the receiver, right
through the cans.
But a stub filter took him out easily, since he was pretty far away (152-ish)
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