On Jul 8, 2008, at 9:47 PM, de W5DK wrote: > We were getting ready to replace the antenna at 580 ft and spend > some money after the dummy load test. Luckily the amp finished > failing. What I relayed locally after this experience was that a > complete system that works flawlessly into a dummy load may not be > flawless.
Don, I think you said you looked at the PA output with a spectrum analyzer prior to its failure -- did you see anything? Was your MASTR II VHF, or UHF? Just curious. I've been fighting VHF MASTR II PA's for years here... I've got (literally) a pile of the continuous-duty PA's that need some sort of repair or another. UHF on the other hand, just work forever. It's a heartbreaker to have watched a friend meticulously rebuild a MASTR II VHF PA including following all the manufacturer specified torques for every single screw, including replacing all the thermal grease correctly with new after cleaning the thing up, using the right solder and heat to put everything back together with the newest mobile components we could find, hooking it to a WELL tested (we were already well into the troubleshooting stage/question of "Why do these things blow up, damn-it!?") commercial antenna fed with good hardline, an isolator, swept with a Sitemaster... yadda, yadda, yadda.... Only to see that one die in 6 months time. Enough to REALLY piss you off -- when your mentors tell you that "there must still be something wrong with the antenna system". Yeah, whatever... at 125 miles round trip to that site, I'm not sure I care anymore at today's gas prices. Tired of replacing the dang things. I think SOME of these in this pile are just old and were abused (overheated) in their lifetimes, but others... like this complete rebuild, were flawless. Then *pop*. Dead. Grrrrr. -- Nate Duehr, WY0X [EMAIL PROTECTED]
