Greg, Thanks for the heads up. Just to make sure you know what I am talking about, this is not a true combiner, since each repeater has a seperate TX antenna, they are not combined. Does the circulator/filter setup still apply to TX antennas in the same proximity?
Thanks, Tracy --- In [email protected], "Gregg Lengling" <[EMAIL PROTECTED]> wrote: > That is poor engineering practice. On any site with multiple transmitters > you must use a Circulator and Low pass filter to prevent mixing in the > amplifier stages. What you have happening is that the possible IM products > that fall within the passband of the amplifier stages are being amplified > and probably are causing your own interference. > > If you go to any website for a combiner company (TX/RX for example), you > will see that on a TX combiner system you will have an Isolator/Circulator > on the output of each transmitter, then fed to at least one 1/4 wave pass > cavity and in most cases a two 3/4 wave cavities. > > Gregg R. Lengling, W9DHI, Retired > Administrator http://www.milwaukeehdtv.org > K2/100 S#3075 KX1 S# 57 > Member: ARRL, RSGB, RCA, WERA and ORC > > > > -----Original Message----- > From: lcradio2002 [mailto:[EMAIL PROTECTED] > Sent: Monday, August 02, 2004 8:07 PM > To: [email protected] > Subject: [Repeater-Builder] Seperate TX / RX antenna questions... > > Group, > I have 3 UHF repeaters (TKR850) at one site, and one is getting some > inteference. The system has a single, top mounted (60') DB420 > feeding a RX multicoupler (Sinclair with a window filter). From > there it goes to each repeater receiver. On the TX side, each > repeater has it's own antenna, a DB408D (there are two TX antenna at > about the 20' level, antennas are about 6' apart horizontally). I > tried running without any cavities or duplexers, and it worked OK, > but one receiver would get hit and key up. I put a single duplexer > can in the RX path and it helped a lot. > > My question has to do with the type of cavity filter to use. I have > some of the MOT square duplexers lying around (BPBR), and some 8" > diameter TXRX cavities (BP only). In a system like this, which is > normally used? Is it normal to put the cavity on the RX side only, > TX side only, or both sides? > > I have never seen a multicoupler / seperate TX antenna system up > close, so I dont know what is normally done in industry. > > Thanks, > Tracy > > > > > > > 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/
