Dave, we did use a Spec Analyzer. to find this problem. Good luck....
73 John VE3AMZ ----- Original Message ----- From: "Dave VanHorn" <[EMAIL PROTECTED]> To: <[email protected]> Sent: Monday, April 10, 2006 5:13 PM Subject: [Repeater-Builder] Re: Aviation Problem Returns, Need Some Help, or a Tuned Stub > --- In [email protected], "John J. Riddell" > <[EMAIL PROTECTED]> wrote: > > > > David, the "Fix" for a Maggiore repeater working in to a > duplexer becoming a "comb generator" > > is to put a small antenna tuner between the TX and the duplexer. > > We fixed a problem here by doing that. > > Tuning the transmitter fixes, filters mask. > Unfortunately without a spectrum analyzer, you'll never know it's in > comb mode. I've done this on three systems, two VHF and one 220, > and they all act about the same. Tune the TX for max output, and > you'll end up on or very near comb mode. Tune with an SA, and you > can see the comb mode go away, as well as another mode with lots of > noise within +/- 100 khz of the carrier go away, while getting to > the same output power. > > > The "Z" matcher that was discussed on here while back would work > as well. > > Possibly, it also acts as a filter to some extent. > The problems I am seeing are in the multiplier chain and many stages > isolate them from the output, so I doubt they are sensitive to load > impedance. There may also be spurs that you can get from the > finals too, NOTHING would surprise me in these things. > > > > > > > > > > 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/
