68
FT-857 Operating Manual
A
CTIVE
-T
UNING
A
NTENNA
S
YSTEM
(
ATAS-100/-120
)
O
PERATION
The optional
ATAS-100/-120
Active-Tuning Antenna System provides operation on a number
of HF bands (7/14/21/28 MHz) plus 50 MHz, 144 MHz, and 430 MHz. The
FT-857
pro-
vides microprocessor control of the tuning mechanism in the
ATAS-100/-120
for conve-
nient automatic tuning.
Before operation can begin, you must instruct the
FT-857
’s microprocessor that the
ATAS-
100/-120
is being used. This is done using the Menu Mode:
1. Press and hold in the [
FUNC
] key for one second to activate the Menu mode.
2. Rotate the
SELECT
knob to recall Menu Mode
No-001
[
EXT MENU
]
, then rotate the
DIAL
to change the setting to “
ON
” to enable the extended Menu Mode.
3. Rotate the
SELECT
knob to recall Menu Mode
N0-085
[
TUNER
/
ATAS
]
. The default
setting for this Menu is “
OFF
.” Rotate the
DIAL
to change the setting to “
ATAS (ALL)
,”
if you are using the
ATAS-100/-120
for all bands (you must connect an external diplexer
to combine the two antenna ports so as to use the
ATAS-100/-120
on all bands). Or
make the setting “
ATAS (HF&50)
,” if you are using the
ATAS-100/-120
on 7 ~ 50
MHz, with a dual-band VHF/UHF antenna connected separately to the 144/430 MHz
antenna port. If you are just using the
ATAS-100/-120
on the HF bands only, with a
dual-band VHF/UHF antenna connected separately to the 144/430 MHz antenna port
(no 50 MHz operation) make the setting “
ATAS (HF)
.”
4. Press and hold in the [
FUNC
] key for one second to save the new setting and exit to
normal operation.
Automatic Tuning
1. Press the [
FUNC
] key, then rotate the
SELECT
knob as needed, to recall Multi Func-
tion Row “k” [
TUNE, DOWN, UP
].
2. Press the [
A
](
TUNE
) key to turn the
ATAS-100/-120
on (this action only supplies volt-
age to the antenna at this point; re-tuning does not begin). The “
ATAS
” will appear on the
LCD.
3. Now press and hold in the [
A
](
TUNE
) key for one second to initiate
ATAS-100/-120
tuning. The transmitter will automatically be activated, a carrier will be sent, and the
antenna’s length will be adjusted for best SWR.
4. If the microprocessor determines that the antenna’s length is radically incorrect from the
optimum value, no carrier will be sent out. Instead, in the receive mode, the antenna will
retract to its longest or shortest position (this may take up to one minute). While this is
happening, do not press the [
A
](
TUNE
) key again.
When the
ATAS-100/-120
reaches its minimum length, automatic tuning will be initi-
ated, and the transmitter will automatically shut off when a satisfactory SWR is achieved.
5. On the 144 MHz and 430 MHz bands, the
ATAS-100/-120
does not require a tuning
process. SWR will be satisfactory when the antenna is fully retracted.
T
RANSMITTER
O
PERATION
