Thanks Paul. I agree with you on everything you said. One thing is for sure, I can't possibly make matters worse!
I finally got to talk to a guy at dbSpectra today. He vaguely remembered the different loops but couldn't remember how they were installed. He was going to try to find some old tech data and send it to me. I haven't seen it yet, but hopefully it's coming. I'll try to take notes and pictures as I go along and send you anything that might be useful for your 'how-to' guide. 73, Mike WM4B From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of Paul N1BUG Sent: Thursday, October 09, 2008 7:20 AM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Desense has me pulling my hair out! (Was DB4060 Duplexer Cables Mike, OK, that makes sense re the 004/005 markings. And OK on the knobs. That really messed with me at first. I thought they were glued or something. It was only when I tried heating one to see if the glue would soften that I found out it was solder! I didn't have any trouble with the top of the inner tube catching on the finger stock when I put them back in, but it was a real close fit getting them in without that happening. On each cavity there were, as I recall, two or three fingers that were sprung inward a little more than the others, possibly having to do with the ends of the two coil springs putting extra pressure on them. Those were the ones I had to watch closely. As long as it hasn't compromised the solder bond of the finger stock in some way, I'm not sure the worn copper plating will do much harm. Of course if the copper plate between the finger stock solder and the inside of the fixed inner tube has deteriorated in any way (which you can't possibly determine by looking), then that would be a serious issue. My guess is it's probably OK. I would just clean them up as best I could and try it. If you can't find someone who knows where the 004 and 005 loops go, I would try an experiment. I would put both 004 on one side of the duplexer, both 005 on the other side. I would then tune it up for high pass on the 004 side (low on the 005) and make a note of the performance measurements (notch depth, insertion loss, VSWR or return loss - measure all parameters on both low and high pass sides of course). Then I would retune it so the 004 side was low pass (and 005 side high pass) and measure the performance again. If there was any difference, I'd go with the configuration that produced the better numbers. If you try this, I would be interested in what you find out. Having said all that, it's also possible the loops were intended to go the way you found them... one 004 and one 005 on each side. That wouldn't be my first guess, but it's possible. It might have something to do with making the impedances look a little nicer or some such... Paul N1BUG Mike Besemer (WM4B) wrote: > Paul, > > I just noticed that what I wrote here was backwards... the 004s had the > strap all the way around and the 005s had the wire extension. > > If I figure out what goes where, I'll let you know. > > Did you have trouble with the top of the inner loop catching on the > fingerstock and tweaking it a bit? I bent a couple of mine, but it tweaked > back into place okay. > > Mike > WM4B
<<image001.jpg>>
<<image002.jpg>>
