P.S. Before I get flame-broiled by the group for "being mean"... Realize that I'm not an ogre, and the answers you're getting from other folks might sound more friendly, and so far, they're all leading the right direction too, it'll just be a long "journey" to get there without the proper test gear.
None of the below is meant in anger or in any way "negative". In fact, you MUST imagine me asking the questions below with a twinkle in my eye and a friendly inquisitive but forceful demeanor to "get" how I would ask the questions in person, if they were posed on the phone, or face-to-face. A repeater guru who taught me once asked, with that same twinkle in his eye, right after I said that "I thought" XYZ was wrong with my repeater... "Are you a thinkin' man, or are you a KNOWIN' man?" :-) <--- NOTE BIG SMILE... and a real one on my face, typing this. Here's something I've always wanted to do, but never had time... write up the learning process I personally went through, including ALL of the annoying things I've chased and troubleshot on repeaters that led me to buy (or beg, or steal... okay, not steal... but you know what I mean) the right test gear over the last number of years. All those "learning experiences" put together in story format, might convince someone that: a) Repeater operation just isn't for them. b) Repeater operation is just bloody expensive to do right. c) Repeater operators are crazy and often spend as much time/money/ effort on really well done repeaters as the most crazed HF contester does on his station. (Yep! That's it!) Nate WY0X On Oct 5, 2009, at 11:37 PM, Nate Duehr wrote: > Just throwing a side-comment in here... > > How do you know if a PA is spurious or if you're bothering your > spectrum neighbors? You MUST MEASURE IT. > > Beg, borrow, or steal the proper test gear for working on repeaters > and this whole "process of elimination by e-mail" disappears... > > Spectrum analyzer, and/or a good RF Service Monitor, a known good- > quality dummy load, "bias T" or directional coupler, high-quality > double-shielded test cables, Bird or other good quality Wattmeter... > all these things really SHOULD make their way into any Repeater- > Builder's box of tricks, sooner or later. > > We've ALL seen repeaters that "worked the 1st time out" without > measuring anything. We've all also seen repeater owners fight and > claw and struggle for months trying to figure out a problem, without > the proper test gear, and wondering if they'll ever figure it out. > > It's soooo much less time-consuming and easier to just measure the > repeater and find the problem than to go back and forth with symptoms > and possible solutions. > > When I started reading this thread, my first thought was "desense > isn't caused by changes in RF power". Of course, I also thought, "The > MASTR II PA is known for going spurious at low power settings, wonder > which PA he has... the little one with only a driver, or a 110W one > that could likely freak out at that low a power." Then the new > symptom that measured SWR was changing with power level... "Oh man, > that thing's probably throwing spurs", I thought to myself... but... > > I kinda refuse to get into guessing games. It just leads to making > more problems you have to fix later if we all guess wrong. > > The way to find out if the PA is spurring, is to look at the output of > the repeater on a Spectrum Analyzer. > > (And if you don't know, how do you know you're within your coordinated > repeater spectrum limits? Is there an adjacent pair repeater above/ > below you? Do you owe it to them to KNOW and not be guessing?) > > Trying to troubleshoot repeaters without begging, borrowing, or > stealing the proper test gear, is kinda like shooting fish in a > barrel, but in a dark cave with no lights on... > > You might hit the fish, or you might blow your foot off. > > Don't wait until the adjacent repeater pair repeater owner sends you > and the coordinator a nasty-gram. Ya know? If you're throwing spurs, > you need to fix your station... and if you don't know if you're > throwing spurs, you need to find out... and the only way to do that > is... > > Measure it. > > -- > Nate Duehr, WY0X > n...@natetech.com
