Re: [Repeater-Builder] Re: Old duplexer tuning question

[Micheal Salem]

Tony: If you are dealing with a bandpass-band reject duplexer, it is usually true that notches will move with the pass cavity.  The pass cavity will tune very broad and the notches tune very sharp.   Trying to line up all the notches is difficult.  Tuning the pass is easier. One technique I use is to try to line up all the passes after summing them (individually tuning them to pass before summing if you can), then individually tune the notches, then redo the pass cavities, then back to the notches.  When I am sure that they are close as they can be, interactively, I then adjust the pass cavity to adjust the notch to maximum depth.  The bandpass is generally broad enough that the slight movement to fine tune the notch doesn't change anything else very much. I tuned up a Phelps Dodge 6 cavity bp-br VHF 600 Khz split duplexer many years ago and still use it successfully on my repeater.  I have tuned up a variety of other duplexers also.  I hope this is helpful.  Micheal Salem N5MS skipp025 wrote: "tony dinkel" <[EMAIL PROTECTED]> wrote: I have been pulling my hair out (I don't have that much more to go) over an old Celwave 6 cavity 526-4 pass reject duplexer. I can get the notches to tune properly one by one but when I put it all back together it just does not seem to sum out right. Is there a procedure someone can point me to? The single vs series adjustments will be different. It would be a pain in the fanny to make the adjustment without a spectrum analyzer with a tracking generator. I tune each cavity, then sum the cavities and readjust the notches, which move quite a bit from the original single cavity position. Once you get the notches in line... firmly secure the notch position adjustment screws and threaten people with early demise should they touch them again. cheers, skipp 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/ YAHOO! GROUPS LINKS  Visit your group "Repeater-Builder" on the web.    To unsubscribe from this group, send an email to:  [EMAIL PROTECTED]    Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.