No. it really IS basic troubleshooting. I've eliminated everything BUT the cans, and I've tried to let that be known here.
Swaptronics is easy. swap out what you have duplicates of and eliminate suspects until you narrow it down to the faulty subsystem component. I spent over 20 years in the Air Force working avionics systems on and off the aircraft. doing a lot of component-level repairs, so I know how to troubleshoot. Nonetheless, these types of duplexers are new to me and have a different set of problems than you'd experience when working with MILSPEC stuff. I've received a lot of great advice here, but I think some folks are jumping in, trying to be helpful (for which I thank them) without reading the whole post and suggesting that I do stuff I've already tried. I know it's not the repeater itself because I've swapped it out. It's not the antenna system because I'm not using the antenna system. I'm gonna tear them down again and clean all the mating surfaces and triple check the fingerstock. Not much else to try. duplexers are not that mechanically complicated. it's the goofy stuff that goes on when you duplex RF that makes it challenging. Thanks, Mike WM4B From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of Unimog Freightliner Sent: Tuesday, October 07, 2008 8:47 PM To: Repeater-Builder@yahoogroups.com Subject: RE: [Repeater-Builder] Re: Desense has me pulling my hair out! (Was DB4060 Duplexer Cables If this was basic troubleshooting then you would have found your problem. Your having a hard time as the list is long with questions. Just trying to help, --- On Tue, 10/7/08, Mike Besemer (WM4B) <[EMAIL PROTECTED]> wrote: From: Mike Besemer (WM4B) <[EMAIL PROTECTED]> Subject: RE: [Repeater-Builder] Re: Desense has me pulling my hair out! (Was DB4060 Duplexer Cables To: Repeater-Builder@yahoogroups.com Date: Tuesday, October 7, 2008, 8:41 PM The problem occurs into both the antenna system and the -8920 with two totally different repeaters. There is no external PA. I've already said that the duplexers are bad. they're the only common component. This is all basic troubleshooting! Mike WM4B From: Repeater-Builder@ yahoogroups. com [mailto:Repeater- [EMAIL PROTECTED] ups.com] On Behalf Of skipp025 Sent: Tuesday, October 07, 2008 5:49 PM To: Repeater-Builder@ yahoogroups. com Subject: [Repeater-Builder] Re: Desense has me pulling my hair out! (Was DB4060 Duplexer Cables > Please explain your first statement. if I can't see it > on the spectrum analyzer, then what is it? Don't know until you nail down the exact cause, which a service monitor might not always clearly indicate, regardless of type and how you use it. > No circulator/isolator in line during test. VSWR is > indetectable between the TX and the cans. Doesn't matter... I've seen and found gremlin generation in well matched cavity and combiner systems. Especially High-Q cavities (most the larger diameter types). Telewave 8 and especially 10 inch cavities seem to be more often prone to gremlin issues when used in tx combiner and antenna systems. Other brands and cavity sizes can also crap up a system when there's a reason or cause. > If I lower the power enough, the desense goes away. just > as I'd expect. It's a matter of scale, after all. I would point an evil eye toward the duplexer, antenna feedline and the antenna. The obvious trick would be to swap out one or more of the mentioned until the problem goes away. > By the way. the symptoms are both the same with 2 separate > repeaters (I amended my first post to say that), so unless > they both have the same problems, the issue is not the with TX. Are you using the same power amplifier with both repeaters? A Circulator might help you quickly locate and/or fix the problem. Type of duplexer, power amplifier, feed-line and antenna you're using? s.
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