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SWR Meter.


An SWR meter is a nice tool to have but has some limitations that you need to know about.  SWR stands for Standing Wave Ratio.  If your antenna is not tuned to the right frequency or has the wrong impedance (RF resistance) a portion of the energy going to the antenna will be reflected back into the feed line and not radiated into space.  When this happens, standing waves appear in the feed line.  Depending on the length of the feed line you may or may not get an accurate picture of what's happening at the antenna.  The best device for tuning an antenna that I have worked with is the MFJ-259.  This gadget will measure the resonate frequency and impedance of your antenna.  It also acts as a frequency meter and a signal generator.  The bad news is that it costs $240 bucks.  I don't know what your local avionics guy would charge to tune your antennas but it might be cheaper than one of these MFJ things.

Larry Coen