Specifications

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. 49 © 2003 SGC Inc
5.1.8.1 Auto Mode
In the Auto Mode, the MAC-200 will select the proper antenna as
well as the proper tuning settings for the antenna from memory if
possible.
Detecting forward power. Once forward power is detected and IF
the MAC-200 is switched to AUTO, the current coupler settings
are sent to the relays and the proper antenna is chosen for
operation. Next, the VSWR is checked and the frequency
measured. If the VSWR is greater than 2:1 or a difference in
frequency is detected, the program branches to the re-tune
program. If it is determined that the VSWR is less than 2:1 and the
frequency has not changed, the computer returns to the Stop mode.
Retuning. Once it is determined that retuning is necessary, a test
is made to see if JP3 is set to tune from memory. If the result is re-
tuning from memory, settings are recalled from the EEPROM
based on the frequency measured. The recalled data is then tested
for validity. If the data proves invalid, it is bypassed and retuning
is performed. If the data recalled proves valid, the data is sent to
the relays and the VSWR is checked. If the VSWR is less than 2:1,
the program branches to the “OK Tuned” section of the program. If
the VSWR is found to be greater than 2:1, the program branches to
the “re-tune” program.
Selecting tuning path. Several tests are made to determine which
tuning algorithm or path should be used to tune the coupler. These
tests are based on frequency, antenna input impedance, antenna
phase, and VSWR. Numerous subroutines are executed repeatedly,
depending on the status of the criteria mentioned above, in order to
achieve proper tuning.