User manual

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5.1.8.2 Manual Mode
When the MAC-200 is operating in manual mode, antenna
selection is made from the front panel switches.
5.1.9 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 re-quires a slightly longer or shorter antenna:
5.1.9.1 Antenna Too Short
Once coupler has verified RF power, tuning sequence proceeds as
follows:
1. Series inductance is added until the phase is deemed
as being inductive.
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2. At this point it is normal for the input impedance to
be low.
3. Input capacitance is added until the antenna is no
longer inductive.
4. The program will continue to increment the series
inductance in .125 µH steps—each time normalizing
the input impedance with 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.
5. The settings that gave the lowest VSWR have been
kept in memory and are now recalled to verify it is a
low VSWR
6. 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 computer reverts to
Stop mode.
5.1.9.2 Antenna Too Long