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14
© 2001 SGC, Inc.
input capacitance until a low VSWR is measured of less than 2:1.
This process will continue until the VSWR has climbed back to
higher than 2:1 or the impedance has become high.
4. The settings that gave the lowest VSWR have been kept in mem-
ory and are now recalled to verify it is a low VSWR
5. At this point the tune indicators are engaged. The current relay
data is saved if JP3 is set to tune from memory; if JP1 is set to tune
elements out during receive position, the program waits until forward
power is no longer present, then removes all tuning elements. The
frequency is saved for future frequency comparison, and the com-
puter reverts to Stop mode.
4.2.2 Antenna Too Long
Once the coupler has verified RF power, the tuning sequence pro-
ceeds
as follows:
1. Output capacitance is added until the phase switches to capacitive.
2. At this point, series inductance is added until the antenna is no
longer capacitive.
3. Fine tuning is performed by trying a small amount of input capaci-
tance (this may or may not be required).
4. At this point, the program executes the same as step 5 (antenna too
short).
The preceding gives a simplified program flow on only two possible
antenna conditions. Much more complex tuning is normally the case.
Further detailed description, however, is beyond the scope of this
manual.
4.2.3 JP1—Tuning Elements Out During Receive
(Factory Default Setting: No)
YES - In this position the software will retain data required in trans-
mit to match the coupler while removing all tuning elements when
no forward power is detected.
NO - In this position the coupler will retain the required tuning data
and will change nothing whether in receive or transmit. If typical
operation is out of band duplex, Yes would be most likely to give
better performance. If in band operation is typical and duplex or sim-
SG-239 Manual
page 14
Wednesday, October 17, 2001 08:31
Composite
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