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That is part of it, especially when the analyzer does not offer port extensions (which are for moving that reference plane without needing to recalibrate). However, you do want to calibrate without the tee. When the coax on one side of the tee is 1/2 wavelength, the path through the tee to the dummy load will be a continuous 50Ω because both the tee and the dummy load are 50Ω. Therefore, calibrating at the port is just fine. You are not taking an impedance measurement, you are taking an SWR measurement which is irrespective of coax length (unless there are major losses or the coax acts as an antenna). Calibrating with the tee would be equally fine, except if you forget you did that and tried using the analyzer after the tee is removed, there will be an error. Calibrating without the tee (in this case at least) will not affect your measurement, but calibrating with the tee will affect future measurements of feed lines connected to an antenna. Therefore, it makes more sense to calibrate without the tee and, using the tee and dummy load, cut the cable using the SWR measurement only. Besides, as [USER=42117]@groundwire[/USER] said, you need an accurate calibration kit to calibrate properly so just leave it alone unless you have a $300 cal kit.

Edit: you can make a cal kit that will likely work fine on 11m for a few bucks, but it will be wrong at higher frequencies, especially VHF and up. Better to just leave it alone.

<blockquote data-quote="brandon7861" data-source="post: 787586" data-attributes="member: 53724">That is part of it, especially when the analyzer does not offer port extensions (which are for moving that reference plane without needing to recalibrate).&nbsp; However, you do want to calibrate without the tee.&nbsp; When the coax on one side of the tee is 1/2 wavelength, the path through the tee to the dummy load will be a continuous 50Ω because both the tee and the dummy load are 50Ω.&nbsp; Therefore, calibrating at the port is just fine. You are not taking an impedance measurement, you are taking an SWR measurement which is irrespective of coax length (unless there are major losses or the coax acts as an antenna). Calibrating with the tee would be equally fine, except if you forget you did that and tried using the analyzer after the tee is removed, there will be an error.&nbsp; Calibrating without the tee (in this case at least) will not affect your measurement, but calibrating with the tee will affect future measurements of feed lines connected to an antenna.&nbsp; Therefore, it makes more sense to calibrate without the tee and, using the tee and dummy load, cut the cable using the SWR measurement only.&nbsp; Besides, as [USER=42117]@groundwire[/USER] said, you need an accurate calibration kit to calibrate properly so just leave it alone unless you have a $300 cal kit.&nbsp; Edit: you can make a cal kit that will likely work fine on 11m for a few bucks, but it will be wrong at higher frequencies, especially VHF and up. Better to just leave it alone.</blockquote>

[QUOTE="brandon7861, post: 787586, member: 53724"] That is part of it, especially when the analyzer does not offer port extensions (which are for moving that reference plane without needing to recalibrate). However, you do want to calibrate without the tee. When the coax on one side of the tee is 1/2 wavelength, the path through the tee to the dummy load will be a continuous 50Ω because both the tee and the dummy load are 50Ω. Therefore, calibrating at the port is just fine. You are not taking an impedance measurement, you are taking an SWR measurement which is irrespective of coax length (unless there are major losses or the coax acts as an antenna). Calibrating with the tee would be equally fine, except if you forget you did that and tried using the analyzer after the tee is removed, there will be an error. Calibrating without the tee (in this case at least) will not affect your measurement, but calibrating with the tee will affect future measurements of feed lines connected to an antenna. Therefore, it makes more sense to calibrate without the tee and, using the tee and dummy load, cut the cable using the SWR measurement only. Besides, as [USER=42117]@groundwire[/USER] said, you need an accurate calibration kit to calibrate properly so just leave it alone unless you have a $300 cal kit. Edit: you can make a cal kit that will likely work fine on 11m for a few bucks, but it will be wrong at higher frequencies, especially VHF and up. Better to just leave it alone. [/QUOTE]

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