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The bottom row of the LCD is intended to indicate the frequency segment where the AATU is tuned. Now you have
to set the needed frequency on the transceiver and to select the needed antenna where the AATU will be tuned.
C A U T I O N
Before giving a tuning command, you have to stop any transmission and put the
amplifier (when available) to bypass (STBY mode). Never apply more than 100W
tuning power in order not to trip either AATU protection!
C A U T I O N
If you use more than one antenna you have to select the proper antenna
corresponding to the needed frequency and/or desired direction.
a)
AUTO TUNE
procedure.
When the antenna is selected and with no RF applied to the AATU, you can start the auto-tune procedure pressing
the button
AUTO TUNE
on the RCU:
Mode: AUTO TUNE .
Apply 10-100W RF ( )
The AATU will then wait for you to apply between 10 and 100W continuous carrier (CW) signal with the desired
frequency. If you leave the AATU waiting longer than 20s, then it will inform you:
Mode: AUTO TUNE
Timeout Expired
When you apply a tuning signal as needed, an asterisk will appear between two brackets at the right-low corner on
the LCD. It will indicate the presence of a proper tuning signal:
Mode: AUTO TUNE .
Apply 10-100W RF ( * )
The process of automatically matching the antenna impedance begins when the power remains constant within the
needed boundaries. After about one second, tuning begins and the indication changes:
Mode: AUTO TUNE .
In Progress … ( * )
This way, the AATU reports that the essential matching process (via impedance measurements and assessment,
and switching the relays) has been initiated in the remote unit. This takes various periods depending on the
frequency and the antenna impedance for this frequency but never in excess of 8s (typically 2s). After the procedure
has finished, the AATU will call to stop tuning power (for at least one second before starting transmission with a
tuned AATU):
Mode: AUTO TUNE .
Stop RF … .
At last, after you stop the tuning power, you will be informed about the results:
Mode: OPERATE .
06970-07110 * OK *
b) Indication.
The frequency segment where the AATU is currently tuned is shown on the bottom line (
к
Hz). It spans about
±
1%
around the tuning frequency that you have applied. Normally you can use this frequency segment with excellent
results without a retune of the AATU.
To the right of the frequency-segment indication, you will see the procedure result as described below.
If for some reason matching cannot be accomplished successfully, the process ends up with a “
SWR>1.5
” or
“
Unstable RF Power”
indication instead of the usual *
OK *
. This is a rare case caused for example by excessive
antenna SWR or unstable tuning power).
