Put a 50 ohm step attenuator in series with the receiver feedline---i.e. between the duplexer and the receiver antenna input. Add attenuation until all desense problems just go away. This is the additional attenuation you need from your duplexer due to the improved sensitivity of your new receiver and increased transmitter power if there is any. All things being "good" and assuming that you haven't added appreciable transmitter power, the repeater should work about as it did before with the attenuator in place. Improve the duplexer to enjoy the improved receiver performance ----that is a repeater that "hears" better than before.
Scott, N6NXI ----- Original Message ----- From: "Brian" <[EMAIL PROTECTED]> To: <[email protected]> Sent: Monday, July 11, 2005 3:39 AM Subject: Re: [Repeater-Builder] VXR-7000 > As far as what has changed....the new piece of equipment(repeater) is > by the specs more then twice as sensitive but on the bench it tested > more like 3 times as sensitive as the old repeater. We are going up > today to try some more testing and I will get back to this thread > with the results. > > > >Brian wrote: > >> Our local club has been running a 10 Yausu 2410 2 meter > >> repeater for many years. It is run through a Wacom wp-641 4 can > >> duplexer. Great results from this unit and it hears excellent....We > >> recently aquired a new vertex vxr-7000 do to some really nice friends > >> locally. In hooking up the new machine we have terrible desense on > >> lower signals that would still be full quieting into our old machine. > > > >First off, just in case of a common mistake: If you replaced the cables > >going to the duplexer and didn't replace them with good quality > >double-shielded cable... stop and go do that right now. > > > >How much isolation is the Wacom providing, since you just had it tuned. > > Did the shop give you a report for what they really got out of it? > > > >Does the repeater desense into a dummy load, or only if the antenna is > >attached? > > > >Do you have a directional coupler and/or Iso-T that you can inject a > >weak signal into the repeater with in both scenarios so you can see if > >the antenna or feedline are part of the problem? > > > >Back to a previous thread - do you have an Isolator on it? Are there > >other high power transmitters near you that could be getting into your > >transmitter? What's the site like? > > > >Do you have any way to see if the transmitter is clean at your selected > >power output level both into the antenna system and into a dummy load? > > > >> We had a local shop retune the duplexer and still no luck. We have > >> tried it both with and without the contorller hooked up and no luck. > >> It hears and transmits great in base mode but falls apart in repeat. > > > >I wouldn't have suspected the tuned cavity first - unless you dropped it > >and dented it or something. Cavity size and frequency are physical > >properties that don't really change much. > > > >Something else is more likely to have changed. > > > >Nate WY0X > > > > > > > > > > > > > >Yahoo! Groups Links > > > > > > > > > > -- > [EMAIL PROTECTED] > Amateur Radio Callsign: KC0DWX > WARN (Weather Amateur Radio Network) member > > > > > > > > Yahoo! Groups Links > > > > > > > Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
