I'm very pleased that you made this request, Greg, because it motivated me to re-assess my changes using before and after photographs and the changes I made to L401 were very subtle in the end. It turns out that BPF peak positions are far more sensitive to L401 windings spacing than RF output power is to corrections made in L511, L512, and L513!
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As I mentioned in my last post, I "over-squeezed" the spacing between L401 turn 1 and turn 19 on my initial squeeze and then attempted to reduce that squeeze and mitigate its impact on the bands below 30m by opening up the spacing between turn 19 and turn 28.
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In this morning's investigation, I used the photo that I posted below (post ?
#130394) as my L401 "before tuning" photo. I had already squeezed L511, L512, and L513 to nearly their final settings to increase my my RF output power but I had not touched L401 yet.
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I just opened-up the sandwich to take the attached "after" board photo. To make the subtle changes more apparent (extremely apparent), I also created an L401-only comparison graphic. The left side of the graphic is the original L401 (blurry side...sorry) and the right side illustrates the state of my final L401.? Pay attention to the angle subtended by the "squeeze" and "expand" sections of the windings. The GIMP too makes this easy!
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The "squeeze" section (yellow) originally subtended about 222 degrees. It now subtends only 198 degrees.
The "expand"? section (blue) originally subtended about 114 degrees. It now subtends about 150 degrees.
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I drafted the comparo graphic rather hastily. I hope it doesn't contain errors but I'll check it tonight. Even so, you and others will get the idea.
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73,
Cal -- AD8Q
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On Fri, Sep 27, 2024 at 04:09 PM, Greg McCain wrote:
<snip>
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Please do post the picture. It needs to be in the WIKI section too. I plan to save it in my personal QMX golden knowledge files store too.
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73 GREG KI4NVX?
