Dave, I've tuned a number of these 633s and had no problems. They are pretty much notch only with wide pass. Often get over 90 db notch with little, less than 1 db, insertion loss.
I would think you have some internal problem, maybe from lightning. Wish I could help more. 73, ron, n9ee/r >From: catdoogan1969 <[EMAIL PROTECTED]> >Date: 2008/06/18 Wed AM 01:54:08 EDT >To: [email protected] >Subject: [Repeater-Builder] 633-6a-2n notch duplexer > >hey guys, > >I've got my hands on a GR1225 repeater with an RFE4000a (Celwave >633-2a-2n) notch duplexer and a phone patch. > >The repeater had some questionable solder problems on the output of >the final due very likely to the poorly tuned duplexer. The solder >was a quick fix and repeater has a healthy 30 watt output with clean >rx (opening about .25uV). > >My current problem is the tuning of this duplexer, I started out with >decent rx at the dx antenna input but no tx power was passing. >Checked with watt meter at the tx port and had full reflect. Tried >retuning tx side and lost rx sens. I can't seem to get either the rx >or tx lined up now. I can get the notches placed right but the pass >portion does not get much higher than -10dB (incoming set to 0dB) >usually lower. > >Is there a start from scratch tuning procedure on these? I contacted >celwave and they gave me a very simple tuning procedure. My problem >is that I do not know what the original frequencies were on this >duplexer. The documentation says that these units are good across >450-470MHz but could there be certain frequencies that they just don't >work well at. > >I am using an IFR 1900CSA Monitor with a tracking gen and a 50ohm load >on the opposite port being tuned. > >Any thoughts on what I am doing wrong would be great...I'm starting to >think I've over-promised on this unit. > >Thanks guys, > >Dave > > > Ron Wright, N9EE 727-376-6575 MICRO COMPUTER CONCEPTS Owner 146.64 repeater Tampa Bay, FL No tone, all are welcome.
