Hi Ian, I'm doing pretty much the same situation in one of my applications. On the lower frequency receiver (radio) I have only a notch cavity set to the other Tx frequency. On the Tx side I have only a band pass cavity set to the Tx frequency. My Tx power is about 2.5 watts all day, every day...
Works fine... cheers, skipp The notch is better placed in the receiver side of things. The bandpass is better placed on the Tx link output. More bang for your buck... ... and I'm using relatively modest Q cavities. > "Kerincom" <kerin...@...> wrote: > > I have considered that to install a notch in the link which is usually a 3 > watt transmitter and I have felt this would be better than notching the 479 > 350 which is the input to the repeater which seems to be reducing its > sensitivity .I am currently using a 6inch cavity filter and a extra 6mc450s > diplexer to notch the signal out and tuned up on a service monitor. The > Repeater uses a 6db on a 9meter mast and the link is connected to a beam at > the bottom of the mast > .If the site was in a better location than I could reduce the link below 1 > watt and it shouldn't affect the 479.350 input but that's hard to do .I also > found some information about using isolators on the transmitters and on the > receiver to filter the signal that is to be removed.I wonder if that would > work better. > > Thank You, > Ian Wells, > Kerinvale Comaudio, > 361 Camboon Road.Biloela.4715 > Phone 0749922574 or 0409159932 > www.kerinvalecomaudio.com.au > > -------Original Message------- > > From: chartmd83 > Date: 14/02/2009 14:18:40 > To: Repeater-Builder@yahoogroups.com > Subject: [Repeater-Builder] Re: Notching nearby frequencies > > Ian, > > What you would like to do is not difficult just may be expensive if > you do not have the filters you would need. > > You described your situation as you want to receive on 479.350 and > you have a link transmitter on 481.825 on the same or nearby antenna. > > As the 481.825 is a link transmitter you may have better luck putting > a Notch filter on the output of the 481.825 that would notch the > 479.350 signal away from 481.825. > > You could stand to loose a few DB on the transmit unless you have a > broad notch filter which would mean you may need more than one to > tighten your notch in favor of 479.350 and allow more pass of the > 481.825. This may mean more insertion loss for the 481 transmit so as > long as you can stand to loose the signal then that should adjust the > interfering frequency better. > > As a note you can use Pass as long as there is enough of it and these > get expensive. > > Jason > > --- In Repeater-Builder@yahoogroups.com, "Kerincom" <kerincom@> wrote: > > > > Hi guys .Can you clarify something for me .I have a repeater that > receives > > on 479.350 and has a link transmitter on 481.825 and I would like to > filter > > the 481.825 out so it doesn't affect the 479.350. I currently have > between > > the diplexer and the 479.350 receiver -a band pass cavity tuned to > 479.350 > > and a notch diplexer tuned to notch the 481.825 . > > I am concerned that this is reducing the receiver sensitivity and > feel I > > would be better to have the band pass between the diplexer and > receiver and > > using a t piece connect the notch to the t piece > > Current setup Diplexer------band pass cavity----notch > diplexer----receiver > > > > Proposed setup Diplexer ------ band pass cavity ---t piece---- receiver > > > > > Notch > > I will try the proposed setup shortly on on a hp service monitor to > see if I > > am better this way > > > > Thank You, > > Ian Wells, > > Kerinvale Comaudio, > > 361 Camboon Road.Biloela.4715 > > Phone 0749922574 or 0409159932 > > www.kerinvalecomaudio.com.au > > >
