Yoon, I have had some RF feedback using my KH1 at times in certain circumstances. ?It was usually on my deck in a stucco sided 3rd floor condo here in Florida. ?I was using my SuperAntenna MP-1 fastened to the deck railing. ?I then put a CMC out 10’ in the feedline and that solved the problem.?
Dave K8WPE
PS ?Now I understand…… He who dies with the most toys has probably forgotten much what he has and why……. So true!
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On Feb 21, 2025, at 4:08?PM, Yoon KM6KJI via groups.io <yoonh.choi@...> wrote:
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On Fri, Feb 21, 2025 at 11:49 AM, Wei AG6AQ wrote:
I was inspired by your post and tried myself with MFJ1720, the major problem is RFI. Have you seen RFI problem in your handheld setting?
Wei, what was the symptom of the RFI problem? Maybe some erratic behaviors of QMX like turning off itself or the keyer suddenly not working, etc.?
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I do remember having that kind of problems when trying handheld operation with different whip antennas and certain lengths of counterpoise wire. I think the problem can be generally minimized with the lowest SWR you can achieve, although there are many other factors affecting the antenna match with HT operation - your hand, head, body and your posture, also the dry or wet ground where you stand on, etc.
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Then I found it very handy to use the reel wire as the counterpoise, with which you can easily find the best match in any circumstances, which will surely minimize the RFI problem. I haven't had the problem with my whip antenna and the reel counterpoise wire.
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73,
Yoon KM6KJI
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David Wilcox K8WPE