Well the figures I took are from memory, but your right, it's more likely about 80 watts out, but at either rate, got the answer that I was looking for. I'm not changing anything here, as it works, and if I mess with it, it WON'T, but one of the students hit me with this question, and I was stunned, so needed the answer. Besides, if I took out two of them it would look odd, and I would never sleep right, they fill the bottom of the rack just fine. Thanks.
Mathew
Ralph Mowery <[EMAIL PROTECTED]> wrote:
--- Mathew Quaife <[EMAIL PROTECTED]>wrote:
> Just for curiosity sake, and please no debates, I'm
> only curious at
> this point for knowledge, and to satisfy a question
> that was asked of
> me. Currently I have a 6 cavity TX/RX duplexer
> system, which has 2.2
> dB of isolation. The system is running 125 watts
> into the duplexer,
> getting just somewhat under 90 watts out. How much
> difference would
> be noticed if the duplexer's were changed to use
> only 4 cans. The
> difference that I am looking at is how much father
> would the repeater
> be heard, versus how far it would hear, how much
> noticable difference,
> considering I get no decense. The repeater is in
> virtually an RF free
> location. Other than the isolation issue, what else
> would fall into
> the matter. Thanks again, as I was asked why six
> cans over 4.
>
> Mathew
>
>
First your measurments are not accurate. For 125
watts in you should get no more than 77 watts out and
that may be a watt or two high.
If you take out one can (assuming the 2.2 db is
correct for 3 cans per side) you gain .73 db which is
hardly enough to notice. That is still assuming that
you do not pick up any desense.
To find out the ammount of change in the range you
have to give the frequency.
A couple of free space calculations using 144 mhz give
an increase of 10 miles to 11 miles and from 37 miles
to 40 miles for the same signal levels. This is free
space and in practice you probably will not see any of
this. The antennas must be able to see each other to
get this change.
If you want to see how this will work in reverse, add
about 12 to 15 feet of some rg-58 coax to your mobile
rig and ride around and see how much range you loose.
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