Phil, Actually you can believe both the K3 and the LP-100A.
The KAT3 is inside the K3, and the SWR it reads is that at the INPUT to the tuner. Tuning the internal K3 tuner will *not* change the SWR on the outside of the K3, it will still be whatever you read on the LP-100A - that is the impedance of your antenna or whatever is connected to the LP-100 output. 73, Don W3FPR On 4/23/2012 3:17 PM, Phil Hystad wrote: > I am trying to learn the behavior of the K3 ATU Tune. I am switching between > two loads. One is dummy load with SWR of about 1.1. The other is a mismatch > on an antenna with a measured SWR of about 4.9 (as read off of the LP-100A > meter). I am attempting to use the ATU Tune button to bring this unmatched > SWR load into a match of 1.5 or under. > > So, I am getting strange results. I can use my external AT1KM tuner to bring > this into a flat 1:1 SWR. If I press the K3 ATU Tune button I also get the > 1:1 SWR reading (or close to it, one bar on the K3 SWR display plut the > LP-100A reads 1:1). If I switch the tuner out of service (into a bypass mode > where the K3 is looking at a 4.9:1 SWR), I use the K3 to hit XMIT briefly and > read out the 4.9 SWR. At this point, it looks like I get a fold back on > power of about 50 percent (operating at 10 watts so fold back to 5 watts I > guess). The next thing I do is switch the AT1KM tuner back into service > without changing anything. When I key down I am getting SWR of 1:1 on the > LP-100A and the K3 but the power is still folded back. If I hit the K3 Tune > button, it quickly tunes and the power is back to full power (or, 10 watts). > > So, my question --- If the K3 folds back power due to high SWR then is it > required to hit the tune button to reset power when you now have a matched > load, 1:1 in this case? > > I hope I have explained the situation, it is a little involved in set up but > I ran across this accidentally while measuring some different antenna loads. > > Also, I am not sure I am reading the SWR on the K3 correctly. If I hit the > tune button for one of my antennas (in this case different from above > scenario) and NO EXTERNAL TUNER, The K3 tunes and a single bar shows up on > the SWR display which I figure is either 1:1 or close to it. But, I have an > LP-100A sitting on the output of my K-line (I have a KPA500 in there but it > is not on during these tests) and the LP-100A gives an SWR reading of 1.73:1. > Who do I believe? The LP-100A was calibrated at the factory (not a kit). > ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
