While you're inside the amp, make sure that the transformer is secure and snug (tighten the bolts if needed, reset the washer and retighten). The pitch of the pop may be a clue as to what is happening (big thump/tiny pop; deep/high pitched etc.).
The transformer and amp module are the only two things that should have any significant heat changes over time. Perhaps run the fan full time to see if it changes the noise? If so, that would indicate it is the module to me. Rick WA6NHC -----Original Message----- From: Ron D'Eau Claire I've not heard it. What gets warm during a transmission is, of course, the RF module heat sink. The RF module is supported by screws into the heat sink on both sides - one side going into an aluminum "Z" bracket that runs down the center of the KPA500 and the other side is secured to the right (looking at the front) side panel behind the handle. I'd start by checking all the external case screws (never pass up an opportunity for an easy fix, Hi!), especially the screws that run across the center of the top and bottom cover, and the screws behind the handle on the side. The screws behind the handle thread directly into the RF module heat sink. The other side of the RF module heat sink is secured to a "Z" bracket that runs down the center of the KPA500 and is secured to the top and bottom covers by the screws running down the center of each. If you built your KPA500 from a kit, you may recall that there are more screws inside the unit that secure the Z-bracket to the side of the RF module. Those aren't as easy to get to but could be the source of your noise. 73, Ron AC7AC -----Original Message----- My KPA500 has developed a heat expansion pop. When it heats up and then cools down I get a pop from inside the amp. It does this now every time I make a SSB transmission. Anyone else experience this? If so, any resolution? Joe N9VX ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
