Yaesu FT-897D, Руководство по эксплуатации

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Page 42 FT-897D O
PERATING
M
ANUAL
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.
T
RANSMITTER
O
PERATION
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.
A
CTIVE
-T
UNING
A
NTENNA
S
YSTEM
(
ATAS-100/-120
)
O
PERATION