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What length did you cut your 1/2 wave of lmr400 too? it has a velocity factor of .85 or 85%.

so for 27.205 which i assume is what you intend centring the antenna on the 1/2 wavelength in that coax should be 4.69m or 15 feet 41/2 inches or thereabouts.If its not then it may explain your slight drop in resonant frequency as could a poor solder joint in one of the plugs,either before or after you changed transmission line.

chances are if you are only using a halfwave of coax to measure the vswr/impedance then your body is too close to the antenna and could interact/detune it,you might be better using 1 wavelength or 1.5 wavelengths of coax.

[QUOTE="jazzsinger, post: 208291, member: 7426"] What length did you cut your 1/2 wave of lmr400 too? it has a velocity factor of .85 or 85%. so for 27.205 which i assume is what you intend centring the antenna on the 1/2 wavelength in that coax should be 4.69m or 15 feet 41/2 inches or thereabouts.If its not then it may explain your slight drop in resonant frequency as could a poor solder joint in one of the plugs,either before or after you changed transmission line. chances are if you are only using a halfwave of coax to measure the vswr/impedance then your body is too close to the antenna and could interact/detune it,you might be better using 1 wavelength or 1.5 wavelengths of coax. [/QUOTE]

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