Operation Manual

Page 40 FT-897 OPERATING MANUAL
ATAS-100/-120 Operating Tips
The information below will help you derive the best perfor-
mance possible from the ATAS-100/-120 Active-Tuning An-
tenna System.
Grounding
It is critically important that you establish a good mechani-
cal and RF ground connection for your ATAS-100/-120 (as
with all vertical antennas). Mobile mounts which are bolted
through the vehicle’s roof, or otherwise mechanically af-
fixed, will usually be satisfactory. However, magnetic mounts
do not provide the RF grounding necessary for good perfor-
mance, and are not recommended for use with this antenna.
Tuning Procedure
The feedpoint impedance of the ATAS-100/-120 (resistance
and reactance) will necessarily vary over a wide range when
you change bands. Occasionally, the transceiver’s micro-
processor will not initially be able to determine the proper
direction for the ATAS-100/-120 to travel (inward or out-
ward) for best SWR.
To resolve this situation, the transceiver will then command
the ATAS-100/-120 to retract fully to its minimum height,
and thence restart the tuning process. In this instance, the
“TUNE” icon will remain on the display after you press the
[
A
](
TUNE
)
key. If this happens, do not press the
[
A
](
TUNE
)
key repeatedly. The transceiver will remain in the receive
mode as it retracts (this may take up to one minute). There-
after, the transmitter will be engaged, and the ATAS-100/-
120 will be automatically adjusted for best SWR. The
“TUNE” icon will then disappear from the LCD, and you
will be ready for operation.
TRANSMITTER OPERATION
External Wattmeters
If you wish to use an external wattmeter in conjunction with
the transceiver and your ATAS-100/-120, please check the
wattmeter with an Ohmmeter prior to installation. Be sure
there is a direct connection between the “In” and “Out” jacks
of the wattmeter (zero resistance), and also ensure that there
is a completely open circuit between the center pin and shield
of the wattmeter’s output jack. Some wattmeters use a coil
or other device which shorts the center pin to ground at DC,
and this type of internal wattmeter circuitry will not allow
the tuning function of the ATAS-100/-120 to operate.
Operation on 30/17/12 Meters
Although the ATAS-100/-120 is not specified for opera-
tion on the above bands, and optimum operation is there-
fore not guaranteed, the ATAS-100/-120 generally can be
tuned successfully on these bands (some manual adjustment
may be required). Operation of the ATAS-100/-120 on these
bands will not damage the antenna’s components; please feel
free to experiment on these bands, if you like.
ACTIVE-TUNING ANTENNA SYSTEM
(
ATAS-100/-120
)
OPERATION