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Figure 1 depicts a situation where normal tuning via the ATU has been successfully completed, and the
tuning data has been stored in the ATU memory. The antenna system SWR as seen by the transmitter is
shown.
In Figure 2, the operator has changed frequency, and the “HI-SWR” icon has appeared. The operator
presses and holds in the TUNE button for one second to begin impedance matching using the ATU.
If a high SWR condition exists (above 3:1), corrective action must be taken in the antenna system to bring
the impedance closer to 50 Ohms. The ATU will refuse to memorize settings on frequencies where the
SWR exceeds 3:1. A High SWR may indicate a mechanical failure in the feed system, and can lead to the
generation of spurious signals causing TVI, etc.
Feed Point SWR
SWR after ATU TuningFrequency
Figure 1
Figure 2
About ATU Memories
SWR (After tuning) Less than 2:1
The tuner settings are stored in the ATU memory.
SWR (After tuning) Greater than 2:1
Tuning data will not be retained in memory. If operation is returned to the same frequency, the tun-
ing process must be repeated.
SWR (After tuning) Greater than 3:1
The “HI-SWR” icon will light up, and the tuner settings, if achieved, will not be memorized. Investi-
gate the high SWR condition and resolve the problem before attempting further operation using this
antenna.
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