User manual

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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,
Mailing: PO Box 3526, Bellevue, WA. 98009
Shipping: 13737 SE 26
th
St. Bellevue, WA. 98005
Toll Free: 800-259-7331 * Phone: [phone] * Fax: [phone]
www.sgcworld.com * Email: [e-mail]
58
depending on the status of the criteria mentioned above, in order to
achieve proper tuning.
Signaling “no-tune.” Should the initial primary tuning sequence
prove unsuccessful, secondary algorithms are attempted until all
possible routines have been exhausted. If, after the secondary
attempts, the coupler still cannot achieve a proper VSWR, the
program branches to a “no-tune” program. Here, the LED’s and
remote tune indicator will blink on and off for about 15 seconds to
tell the user a proper VSWR could not be found. After the
indicators stop blinking, the program waits for forward power to
cease (if it has not ceased al-ready) and returns to stop mode. At
this point the user should try several other frequencies. If the “no-
tune” condition persists, check the installation of the antenna,
coupler, radio, and ground system for possible problems.
Signaling “OK tune.” If the coupler achieves a good VSWR
during the tuning sequence, the program branches to the “OK
Tune” section of the code. Here, the tune indicators are engaged. A
test is then made to check if JP3 is set to tune from memory. If so,
the frequency is measured and the tuning elements used are saved
in memory coupled with a verification code. Once saved, a test is
made on JP1 to check if the duplex mode has been selected. If so,
the transmit tuning elements remain in circuit until the receive
mode is verified. At this time, all tuning elements are removed.
The frequency is then saved for future comparison and the CPU
reverts back to the STOP mode.