Mathew,
Four miles range from a handheld is not that bad with an antenna at 60
feet. Then consider the almost 20 db power advantage that your transmitter
has over the user's handheld, about 3 1/2 S units. You didn't mention the
band you are using or your antenna type, what kind of receiver, transmitter,
terrain, etc. These are going to affect what you should expect out of your
system.
"...their signal is not really that bad." Could be many things; off
freq, too little PL, too much PL, over deviation, not enough hi-pass
filtering in their HT transmitter, rpt receiver bandpass very narrow. Put a
scope on your rpt disciminator for clues. Also, look at receiver limiting
and see if it changes during modulation. Could be an IF alignment issue.
FWIW, an isotee can be constucted in about five minutes from a UHF tee.
Unscrew the male pin, push out the female section, saw off one end of the
female section leaving the threaded portion intact, and reassemble. Then
mark the end with no center conductor with red paint, magic marker or
something, to designate the isolated end. (Not marking the isoport will
eventually cause you grief!) Plug your Cushman into the isolated port and
expect 20 to 30 db loss though the port, depending on your frequency. You
can leave the isotee in line permanently for testing, sytem reformance,
degradation over time, etc.
73,
Al, K9SI
> Date: Tue, 27 Jul 2004 00:01:58 -0000
> From: "w9mwq" <[EMAIL PROTECTED]>
> Subject: Receiver Sensitivity Testing Through Duplexer
>
> I need a little advise here. I want to test my repeater's
> sensitivity through the duplexer's while the transmitter is keyed
> up, into my Cushman Service Monitor. What is the best method of
> doing this? Do I need an isolator of some sort, or will the service
> monitor handle both the incoming power and the outgoing signal
> generator? It's a Cushman 6030 by the way. The repeater is working
> excellent for the most part. The problem that I am having is on
> weak signals, the audio is being chopped out, almost like the PL
> deck is shutting down. On the bench, the receiver is at about .25
> microvolts sensitivity at 12 DB Sinad. Audio out of the transmitter
> is about 4KHz wide, and clean at 100 watts. Any suggestions.
> Handhelds are able to get in from about 4 miles away, mobiles have
> no troubles at 30 miles away. The antenna is only up at 60' right
> now, fed with 120' of 7/8" Andrews hardline. But it seems the
> handhelds are the one's having the problems, and their signal is not
> really that bad. Help please.
>
> Mathew
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