Active-Tuning Antenna System (Atas-100/-120) Operation; Automatic Tuning; Manual Tuning - Yaesu FT-897 Operating Manual

A -T
CTIVE UNING
The optional ATAS-100/-120 Active-Tuning Antenna Sys-
tem provides operation on a number of HF bands (7/14/21/
28 MHz) plus 50 MHz, 144 MHz, and 430 MHz. The FT-
897 provides microprocessor control of the tuning mecha-
nism in the ATAS-100/-120 for convenient automatic tuning.
Before operation can begin, you must instruct the FT-897's
microprocessor that the ATAS-100/-120 is being used. This
is done using the Menu Mode:
1. Press and hold in the [ F ] key for one second to activate
the Menu mode.
2. Rotate the MEM/VFO CH 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 com-
bine 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 sepa-
rately 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)."
3. Press and hold in the [ F ] key for one second to save the
new setting and exit to normal operation.

Automatic Tuning

1. Press the [ F ] key, as needed, to recall Multi Function
Row "k" [ TUNE, DOWN, UP ] .
2. Press the [ A ]( TUNE ) key to turn the ATAS-100/-120 on
(this action only supplies voltage to the antenna at this
point; re-tuning does not begin). "Parentheses" will ap-
pear on the both sides of the "TUNE" indication, and the
"ATAS" will appear on the LCD.
3. Now press and hold in the [ A ]( TUNE ) key for one sec-
ond 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 an-
tenna will retract to its 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 initiated, 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 sat-
isfactory when the antenna is fully retracted.
6. When you wish to conclude ATAS-100/-120 operation,
press the [ A ](TUNE) key; the "Parentheses" disappear
surrounding the "ATAS" indication.
FT-897 O M
PERATING ANUAL
A S
NTENNA YSTEM
T
RANSMITTER
ATAS-100/-120 O

Manual Tuning

In some instances, the SWR may be slightly improved by
manual adjustment of the antenna position. This may be
needed for operation on bands like 40 meters, where the
"Q" of the ATAS-100/-120 is high, causing a narrow reso-
nance range.
Before Manual Tuning, press the [ F ] key, as needed, to re-
call Multi Function Row "i" [ MTR, -----, DISP ] , then press
the [ A ]( MTR ) or [ B ] key to change the meter function to the
SWR meter ("SWR" icon will appear at the upper of the
[ B ] key).
To tune the ATAS-100/-120 manually, recall Multi Func-
tion Row "k" [TUNE, DOWN, UP], then press and hold in
the microphone PTT switch. With the transceiver in the
"transmit" mode, press and hold in the [ C ]( UP ) key (to raise
the antenna) or the [ B ]( DOWN ) key (to lower the antenna).
While you hold in one of these keys, the FT-897 will gener-
ate a carrier, and you may watch the top scale of the FT-
897's meter, looking for the meter indication to reach its
minimum value. When this is reached, release the [ C ]( UP )
or [ B ]( DOWN ) key, then release the PTT key to return to
the "receive" mode.
1) Once automatic matching has been success-
fully accomplished, you must change frequency
by at least 10 kHz before attempting automatic
matching again. Within a window of ±10 kHz from a
match point, the transceiver's microprocessor will ig-
nore any command to attempt automatic matching.
2) Antenna tuning is accomplished using a "CW" car-
rier, although the mode indication will not change to
"CW" (if you are operating on another mode) during
antenna tuning.
3) If you see a "HI SWR" on the LCD, it may mean that
there is a problem in your coaxial cable (bad connec-
tion, etc.) which is preventing successful tuning. Re-
place the cable, or try adding a few feet/meters of cable
(to eliminate the possibility of adverse "transformer ac-
tion" in the 50Ω cable during the tuning process).
4) If you are able to achieve an SWR of less than 2:1 via
manual tuning, the FT-897 will "accept" the manual
setting, and you may then re-tune automatically when
changing bands. If, however, you stop manual tuning
at a non-optimum setting (SWR >2:1), the FT-897 will
not permit further automatic tuning. To refresh the set-
ting of the ATAS-100/-120, press the [B](DOWN) key
until the ATAS-100/-120 fully retracts. You may then
restart automatic tuning per the procedures described
earlier.
5) The FT-897 may also be used with the model ATAS-100
antenna, although the tuning speed of the ATAS-100
will be slower than with the ATAS-120.
O
PERATION
PERATION
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