Yaesu FTDX-9000MP Operation Manual

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Page 85FT DX 9000MP OPERATION MANUALUSING THE AUTOMATIC ANTENNA T UNERABOUT ATU O PERATIONFigure 1 depicts a situation where normal tuning via the ATU has been successfully completed, and the tuning data has beenstored in the ATU memory. The antenna system as seen by the transmitter is shown.In Figure 2, the operator has changed frequency, and the HI SWR LED has become illuminated. The operator presses andholds in the TUNE switch (# ) for two seconds to begin impedance matching using the ATU.If a high SWR conditions exists (above 3:1), corrective action must be taken in the antenna system to bring the impedancecloser to 50 Ohms. Besides the fact that the ATU will refuse to memorize settings on frequencies where the SWR exceeds3:1, the high SWR may indicate a mechanical failure in the feed system, and such failures can lead to the generation ofspurious signals causing TVI, etc.About ATU MemoriesSWR (Post-tuning) Less than 1.5:1The tuning settings are committed to the ATU memory.SWR (Post-tuning) Greater than 1.5:1Tuning data will not be retained in memory. If you return to the same frequency, the tuning process must be repeated.SWR (Post-tuning) Greater than 3:1The HI SWR LED will light up, and tuning settings, if achieved, will not be memorized. Please investigate andresolve the high SWR condition before attempting further operation using this antenna. The high SWR may indicatea mechanical failure in the feed system, and such failures can lead to the generation of spurious signals causing TVI,etc.SWR = 1.0SWR = 1.5SWR = 2.0Frequency SWR Seen by ATUFeed Point SWRFigure 1Figure 2SWR = 1.0SWR = 2.0SWR = 3.0① ②FrequencyMemorized SWRRetunigMemorized ATU SettingRetuned SettingSWR after ATU TuningFeed Point SWR