Hi Gary, I haven’t seen that problem unless the SWR was at least 1.4:1. However, it’s possible you have hit just the wrong phase angle. If your 1.2 SWR resulted in a load impedance of 42 Ohms, the current could go up 20 percent. On the other hand, 55 A into 50 Ohms sounds a bit high. Make sure the voltage isn’t dropping more than a couple Volts.
73, Scott K9MA ---------- Scott Ellington --- via iPad > On Mar 15, 2019, at 1:25 PM, Gary J Ferdinand <alapa...@w2cs.net> wrote: > > I’m in the process of checking out my amp. I have two dipoles (40 and 80). > At resonance both show a 1.2:1 SWR with ATU totally bypassed. With ATU on, > it remains bypassed on 80, but shows only the ATU ON LED on 40. In both > cases the resultant SWR is 1.2:1. SWR measurements are from the KPA1500 > display. > > When I use the amp with my K3 and drive it up to 1500W, I am occasionally > getting an excessive PA current fault at 63A. From a cold start it’s 60A, > but as it warms up in contest usage I find the power drops off, so I have to > adjust the K3 to bring it back up to 1500W. At that point the PA current > goes over 60A. > > Interestingly, into a dummy load the 1500W point shows a PA current of only > 55A. So the 1.2:1 SWR, be it via a bypassed ATU or using the ATU, is > sufficient to raise the PA current eventually to excessive levels. > > Suggestions? I don’t want this to be flipping out during a contest. I also > don’t want to reduce power into what should be a totally acceptable load. > > 73 > > Gary W2CS > > > ______________________________________________________________ > 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 ______________________________________________________________ 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
