If you have 75 ohm coax, I would just try it. If the Z of the antenna is in fact around 35 ohms, the Z at the shack end may be close to 35 ohms on some bands, but on others the Z will be transposed to well over 100 ohms with an SWR probably over 3 to one. One of my dipoles has a SWR at the top of 75 meters of approximately 4:1, and I occasionally venture up there, but my K3S with internal tuner does not complain and quickly matches it to about 1:1. Not ideal and this is not the way I usually build my antennas, but the loss is not too bad. If you can build a unun with approximately a 1:2 ratio this should solve your problem. If it does not cover all the way from 80 to 10 with low loss, I would not worry too much about say 10 and 12 meters now, since some loss, and/or lower power output should not be a problem with our sunspot situation. If you happen to have lots of 75 ohm cable, you could parallel two runs of exactly the same length, the pair would have a Z of 37.5 ohms, so nearly perfect if your actual antenna Z is in the vicinity of say 25 to 45 ohms. Not suggesting you spend much money on the coax, but if it is cheap or free, you could do this. Later if you change antennas you would have an extra coax run already in place. The power handling of the dual coax runs would be at least the same as a single run, and the loss could be either slightly higher or lower with the dual run depending upon whether the loss is I squared R, or due to the dielectric characteristics, but I would be surprised if the loss differed much at the HF frequencies. Just another idea to think about, not necessarily a recommendation. Rick KL7CW
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