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To show what bob85 is referring to I ran a scan of a 75 ohm test load at the end of a 50 ohm coax.

Shockwave said he changed out the feedline to different lengths to account for different wavelengths of feedline. I, however, am using a different method to achieve the same goal, I am opting to change the frequency itself as opposed to changing the actual feedline. In the end the two methods have effectively the same end results, however, with my VNA this is the easier method to use.

The two graphs are are the same, except for different data points for the information at the right. Due to the transformer action of the feedline over a range of frequencies you can see how R varies based on the varying wavelength/coax length.

One last chart just to confirm a point made in this and other threads.

This is the same chart as above only with the SWR line added. As you can see the change in SWR is barely noticeable across the chart, even with rather large variances R and X comparatively.

The DB

<blockquote data-quote="The DB" data-source="post: 434464" data-attributes="member: 21346">To show what bob85 is referring to I ran a scan of a 75 ohm test load at the end of a 50 ohm coax.Shockwave said he changed out the feedline to different lengths to account for different wavelengths of feedline.&nbsp; I, however, am using a different method to achieve the same goal, I am opting to change the frequency itself as opposed to changing the actual feedline.&nbsp; In the end the two methods have effectively the same end results, however, with my VNA this is the easier method to use.<img src="http://hittman.us/pictures/75ohm-highR.jpg" alt="" class="fr-fic fr-dii fr-draggable " data-size="" style="" /><img src="http://hittman.us/pictures/75ohm-lowR.jpg" alt="" class="fr-fic fr-dii fr-draggable " data-size="" style="" />The two graphs are are the same, except for different data points for the information at the right.&nbsp; Due to the transformer action of the feedline over a range of frequencies you can see how R varies based on the varying wavelength/coax length.One last chart just to confirm a point made in this and other threads.<img src="http://hittman.us/pictures/75ohm-SWR.jpg" alt="" class="fr-fic fr-dii fr-draggable " data-size="" style="" />This is the same chart as above only with the SWR line added.&nbsp; As you can see the change in SWR is barely noticeable across the chart, even with rather large variances R and X comparatively.<a href="http://hittman.us" target="_blank">The DB</a></blockquote>

[QUOTE="The DB, post: 434464, member: 21346"] To show what bob85 is referring to I ran a scan of a 75 ohm test load at the end of a 50 ohm coax. Shockwave said he changed out the feedline to different lengths to account for different wavelengths of feedline. I, however, am using a different method to achieve the same goal, I am opting to change the frequency itself as opposed to changing the actual feedline. In the end the two methods have effectively the same end results, however, with my VNA this is the easier method to use. [IMG]http://hittman.us/pictures/75ohm-highR.jpg[/IMG] [IMG]http://hittman.us/pictures/75ohm-lowR.jpg[/IMG] The two graphs are are the same, except for different data points for the information at the right. Due to the transformer action of the feedline over a range of frequencies you can see how R varies based on the varying wavelength/coax length. One last chart just to confirm a point made in this and other threads. [IMG]http://hittman.us/pictures/75ohm-SWR.jpg[/IMG] This is the same chart as above only with the SWR line added. As you can see the change in SWR is barely noticeable across the chart, even with rather large variances R and X comparatively. [URL="http://hittman.us"][COLOR="Black"]The DB[/COLOR][/URL] [/QUOTE]

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