I built this lumped component combiner to run two lowish power, cheap to build Class D amps combined on 137khz. (2200 meters) Whilst it worked the drain waveforms were like those into a very poorly matched antenna load, so I went with a Wilkinson using ferrite beads to make two lengths of Teflon co-ax act as 1/4 waves and a ferrite cored auto transformer. This works well but I want, for the knowledge, to see if I can make the lumped component one work properly. I believe this to be a narrow band, high Q device. Given I have a decent sig gen and scope and access to a very decent SA, can anyone explain in simple terms how I might "tune" it with regard to coil turns or cap values, on the bench, at low power as from the sig gen, to better resonate it please? Thanks. I link to the lumped device and the schematic of the Wilkinson with ferrite, albeit I now use an auto transformer unlike the schematic. Lumped component I want to tweak to my desired frequency is at: https://www.amateurradio.com/630m-wilkinson-power-combiner/ Combiner that works fine : http://www.w1vd.com/137-500-500WCombiner.pdf Thanks for any replies.