SG-231 MANUAL
SGC Inc. SGC Building, 13737 S.E. 26th St. Bellevue, WA. 98005 USA
© 11/00 SGC, Inc.
P.O. Box 3526, 98009 Fax: (425) 746-6384 Tel: (425) 746-6310
E-Mail: [email protected] Website: www.sgcworld.com
43
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 already) 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 JP2 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.
8.2 Tuning Paths
As mentioned previously, various tests are executed to determine the most logical
tuning sequence to be performed. Dependent on the test results, additional tests and
appropriate sub-routines are executed throughout the tuning process. Following are
examples of the activity that occurs when the coupler must be matched to a frequency
that requires a slightly longer or shorter antenna:
8.2.1 Antenna Too Short
C in
L1
5 0 ohms
Antenna
Once the coupler has verified RF power, the tuning sequence proceeds as follows: