tests and appropriate sub-routines are executed throughout the tuning
process. Following are examples of the activity that occurs when the tuner
must be matched to a frequency that requires a slightly longer or shorter
antenna:
9
9..3
3
A
An
ntte
en
nn
na
a
T
To
oo
o
S
Sh
ho
or
rtt
Once the tuner has verified RF power, the tuning sequence is as follows:
1.
Series inductance is added until the phase is deemed as being
inductive. At this point it is normal for the input impedance to be low.
2.
Input capacitance is added until the antenna is no longer inductive.
3.
Tests are conducted continuously on the VSWR phase and input
impedance. As long as the VSWR is greater than 4:1, the program will
continue to increment the series inductance in .25
µ
h steps - each
time normalizing the input impedance with input capacitance.
4.
When the VSWR goes below 4:1, the computer will retain the data it
determines is less than 2:1 until input impedance is no longer low or
VSWR climbs higher than 2:1. The previous data is then tested once
again to verify validity.
5.
At this point the tune indicators are engaged. The current relay data
is saved if 'J-3' is set to tune from memory, and if 'J-2" is set to the
tuning elements out during receive position, the program waits until
f o r w a r d p o w e r i s n o l o n g e r p r e s e n t , t h e n r e m o v e s a l l t u n i n g
elements. The current frequency is saved for future frequency
comparison, and the computer reverts back to the "sleep" mode.
59
© 1998 SGC Inc
SG-230 Manual
SGC Inc. SGC Building, 13737 S.E. 26th St. Bellevue, WA 98005 USA
P.O. Box 3526, 98009 Fax: 425-746-6384 Tel: 425- 746-6310 or 1-800-259 7331
E-mail: [email protected] Web site: http://www.sgcworld.com
C in
L1
50 ohms
Antenna