You didn't mention the small capacitor - that one sets the reject freq - very important that each cavity has the same degree of coupling hence the rotate for 8 db dip routine.
ssb ----- Original Message ----- From: "Ralph Mowery" <[EMAIL PROTECTED]> To: <[email protected]> Sent: Thursday, November 06, 2003 9:41 PM Subject: Re: [Repeater-Builder] Re: 220 Duplexer Tuning Help | : Re: [Repeater-Builder] Re: 220 Duplexer Tuning Help | | | > Maybe I'm missing something then. All I'm adjusting is the rod and | turning | > the coupling. | > | > There is a small hex cap on top of the coupling, that I didn't touch. | > | > The manufacturers tuning instructions for this model say to adjust an | > external tuning stub, which I don't have. | > | > | YOu may be missing something. I have the instructions for a wp652 but not | the A version. There was a 450 mhz version that I seem to remember having | some adjustments for the rejection notches under a cover on the top of each | can similar to what you are describing. That may have taken the place of | the reject stubs that are on the side of the cans. They looked similar to a | pl-259 with a clear plastic rod sticking out of them and parallel to the | cans. You may want to adjust the coupling loops for maximum output and then | adjusting the large tuning adjustments for maximum pass. Then look under | the covers and adjust the screws for maximum rejection. The notches for | maximum rejection have to be adjusted last. | | A repeater group I was with had a 4 can 2 meter duplexer from them and we | has lots of problems with intermod. The duplexer worked ok for a 30 watt | repeater but many times it had lots of intermod from what seemed like about | 100 transmitters within a 3 block radius. We sent it off the Wacom and had | a band pass cavity put on the TX and RX side. This cleared up the problem . | Noticed that in a catalog a year or so later that same design showed up. | | Seems like some duplexers just do not have much out of band rejection. | | | | | | | | Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/ | | --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.535 / Virus Database: 330 - Release Date: 11/1/2003 Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
