2m Moxon Update

I did some tests of the 2m Moxon with the FT-2900R and an SWR/Watt meter. I wanted to check the SWR to evaluate the overall matching. I set the antenna up indoors on a tripod up about 4 feet and connected it to the radio through the meter. Starting on low power 5W at the simplex frequency of 146.52Mhz I had an SWR of 1:1. Same on 10W. At 30W I was reading an SWR of 1.5:1 and at 75W the SWR was close to 3:1. This was not unexpected behavior as the way I built the Moxon I have the feedline running through the middle of the RF field. This is not an issue with low power but at high power it puts RF on the feedline. I wound about 6 turns of coax on the feedline and the SWR dropped to about 2:1. Adding a snap on ferrite bead with three turns of coax running through it further reduced the SWR at 75W to about 1.6:1. Aside from this issue, which is easily solved with an air choke on the feedline, it looks like the 2m Moxon is ready for testing at some height and will be ready for full power from the FT-2900R.


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