I purchased a 70 Watt Amplifier Kit and built it Unfortunately, the kits do not come with any instructions. I have managed to find a variety of web sites where people built the amp and offered perspective. The kit seems to be shipped in varying configurations. In any case, I built it and it does not work properly. It basically amplifies, but the input SWR as seen by my Ham radio is high. I am using a 50 Ohm dummy load to test output. Here is a link to one site describing the amp/more info https://www.qsoshack.com/make-a-45-watt-linear-amplifier/ There are many other sites describing it and the build. The picture below shows the input transformer labelled as having a 2T:0.5T turns ratio. When the amplifier is active, the input signal from my radio goes thru an inductor(the transformer) to ground. My radio sees a high SWR (at 3.9 MHZ). The resister labelled R6 (18 Ohms in my build)/Vertically placed was not described on some web sites, but others said to include it. The resister is over the secondary side of the transformer. Some said to use 21 Ohms, some said 15 ohms. A table was shown of SWR over various choices of R6 choices. The resister is over these two contact areas. What circuit components are needed to reduce the SWR as seen by my radio. I am going to try a 15 Ohm resister on the secondary instead of my 18 and see how that works. One person mentioned to use a variable cap in series with the transformer input and tune it. I wish to have a decent SWR on the 20 and 40 meter bands (at the very least). Like to have 1.5 or less. I have a nanovna and can test with that. If I can do a sweep and show the smyth chart or swr, would that help? I am also contemplating modeling this in LTSPice but wonder about my modelling skills as the schematic is somewhat less descriptive. I feel that this should boil down to a calculation of what component I need and where it should be placed as determined by a smyth chart. I dont really know those charts , but the nano might be helpful . I just want this swr 1.5 or less by adjusting the circuit with the rigt compoent(s) and have it stay like that on as many bands as possible. The amplifier has its own problems in terms of cleanliness of signal and heat dissipation. Please offer some pointers as to the route I should take. I have been reading up on transformers and how power is conserved and the secondary resister will show up on the input side thru the turns ratio, but wonder how that can fix this over multiple bands.