John, Get the preamp out of the circuit and **powered down.** Preamps will take any desense probelm and will make them worse - usually at twice the value of their gain.
Do a 'binary search' - Start by getting it to work without stuff. Disconnect the antenna and feedline and put a dummy load on the output of the duplexer. Inject or leak a weak signal into the system and turn the TX on and off. If you don't have a service monitor, a talkie on low power into a dummy load at some distance will usually work. If the noise level changes you still have a problem, so move the termination to the transmitter output. If not the problem's in the antenna or feedline so terminate at the end of the feedline and repeater the test and so on. Divide the part that doesn't work in two and figure out what half is broken. Oz jmp46534 wrote: > > > Hi, > > I have read the large majority of messages on here and the Repeater > builders site, and I am still lost. > This is the first time I have worked with a repeater in my 30 year ham > career and am learning something new everyday.. > > We installed a GE Mastr II running into pre-amp, a BandPass and then a > 6 can duplexer. The antenna is Hustler G7-144 and 1/2in hardline up 65 > feet. > > The duplexer was set up with service monitor at the test site prior to > installing it here. > > When I go above 10 watts out all we hear from the users is a lot noise > and very little voice. As the power goes higher (when radio heats up) > the noise gets so bad that we can not make out a thing the people are > saying. > > The SWR between the radio and the duplexer is 1.1 at 5 w and 1.15 at > 7.5 watts. Of course as we go up in power to 20 watts out we have 1.3 SWR. > > On the antenna side of the duplexer the SWR goes up to 1.4 at 20 watts > and 1.2 at 7 watts and very little at 5watts (meter hardly moves). > > I am thinking it is either the hardline or connectors and/or antenna. > > The antenna and hardline are used. The connectors despite being new > are very hard to put on. The guy that installed them even had to use > pliers on the tower to attach the connector up there and I have to use > pliers to get it tight on the duplexer. > > Any suggestions on how to fix this? > > Thanks and 73 > John, W3ML > > -- mailto:o...@ozindfw.net Oz POB 93167 Southlake, TX 76092 (Near DFW Airport)
