i have been using the icom at-500 automatic antenna tuner for six months, and it is a great piece of gear. however, there is a very minor modification i performed to the tuner to better suit my needs.
the tuner automatiacally selects one of four antenna s0-239 connectors on the back depending upon which band you are operating. many of us utilize one feed line for an 80 and 40 meter dipole or inverted vee. the at-500 (and at-100) has two seperate antenna terminals for these bands. if you desire to use one feed line for both of these lower band antennas, you either have to install a coax switch and manually switch the tuner in line, or unscrew the pl-259 connector from one antenna terminal and install it on the other. all of this is inconvenient and defeats athe purpose of an automatic tuner. the mod i performed is extremely simple. i moved the wire going to antenna terminal #3 and moved it to terminal #2. this directs the 80 meter rf to the same terminal as the rf for 40 meters and allows one to use the same antenna terminal for both bands and one feed line. to perform the change, remove the top cover of the tuner, locate the two correct terminals using page 6 of the manula, unsolder the one to be move, and s9lder it to the correct terminal. the terminals are easy to reach. just be sure all connections are good.
