After closer inspection, I found that the jumper had indeed unsoldered itself. I had to take the cover off of the harmonic filter to find it. The jumper was black on bottom and the solder was black also. On the inside of the cover were black deposits and a little bit of solder that had been ejected from the joint. I check the board closely for more stray solder, cleaned up the solder and installed a new jumper as described on the repeater-builder website. I'll know if it worked this afternoon. I cooked my Astron 35 Amp PS a few weeks ago so now I don't have a way to test power amps at home.
Jamey Wright Systems Analyst Morgan County EMCD 911 Decatur, Al 256-552-0911 -----Original Message----- From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of [EMAIL PROTECTED] Sent: Monday, June 06, 2005 8:01 PM To: Repeater-Builder@yahoogroups.com Subject: RE: [Repeater-Builder] Mastr II UHF Station PA Failure If the heatsink was very hot, then I would assume that the PA transistors were working. Obviously, there are better methods to verify this. But lets say they were working, I would check the jumper between the PA & filter boards. This is a common failure point on UHF PAs as well. Does your filter board have tuning capacitors on it? Stations that came from the factory in a duplex configuration usually had the tunable filter boards. I've seen where the tuning caps have become problematic as well. Make sure the balancing resistors are intact on both the input and output sides of the PA transistors. If one side is charred, then I would suspect a bad transistor. 73, Bryan N3ST -----Original Message----- From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] Behalf Of Jamey Wright Sent: Monday, June 06, 2005 7:47 PM To: repeater-builder@yahoogroups.com Subject: [Repeater-Builder] Mastr II UHF Station PA Failure When I went to work this mornining, I noticed that the signal level from the repeater seemed to be down a little. I contributed it to band conditions and decided to check it after work. As I was leaving work, I got a phone call saying the repeater was hung in transmit. This was caused by a power glitch or brownout from storms causing a controller problem. I arrived at the site 45 minutes later and found the transmitter keyed. There is a fan on the cover of the PA that blows across the components but the heat sink fins were too hot to touch. I shut off the power supply but allowed the fan to run while I diagnosed the controller problem. The PA was set for 75 watts out. When I checked it, the power was 4 watts and would creep up to 5 watts after 30-45 seconds. This is a Mastr II repeater PA. The number on the board is PL19D423006G2 Rev C. I didn't look the number up but I assumed the writing on the PA cover that said 75 watts was correct. Any suggestions on what and where to check for problems? I don't see any crispy critters on the board but some of the components are discolored. They look like silver thay has been exposed to oxygen. Does the UHF PA suffer from the PA output to filter network jumper problem? Thanks in advance. Jamey Wright KD4SIY 444.325 Wilson Mtn/Oden Ridge, Al Yahoo! Groups Links ___________________________________________________________________ The information contained in this message and any attachment may be proprietary, confidential, and privileged or subject to the work product doctrine and thus protected from disclosure. If the reader of this message is not the intended recipient, or an employee or agent responsible for delivering this message to the intended recipient, you are hereby notified that any dissemination, distribution or copying of this communication is strictly prohibited. If you have received this communication in error, please notify me immediately by replying to this message and deleting it and all copies and backups thereof. Thank you. 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/
