Using The Automatic Antenna Tuner; Atu Operation - Yaesu FT-950 Operating Manual

U
SING THE
The Automatic Antenna Tuner (hereinafter referred to as the "ATU") built into each FT-950 is designed to ensure a 50-
Ohm load for the final amplifier stage of the transmitter. We recommend that the ATU be used whenever you operate on the
FT-950.
A :
DVICE
Because the ATU of the FT-950 is located inside the station, it only adjusts the impedance presented to the transceiver
at the station end of your coaxial cable feedline. It does not "tune" the SWR at the antenna feed point itself. When
designing and building your antenna system, we recommend that every effort be made to ensure a low SWR at the
antenna feed point.
The ATU of the FT-950 includes 100 memories for tuning data. Eleven of these memories are allocated, one per
Amateur band, so that each band has at least one setting preset for use on that band. The remaining 89 memories are
reserved for the 89 most-recent tuning points, for quick frequency change without the need to retune the ATU.
The ATU in the FT-950 is designed to match impedances within the range of 16.5 Ohms to 150 Ohms, corresponding
to an SWR of 3:1 or less on the 160 through 6 meter amateur bands. Accordingly, simple non-resonant whip antennas,
along with random-length wires and the "G5RV" antenna (on most bands) may not be within the impedance matching
range of the ATU.
1. Use the Main Tuning Dial knob to set the radio to the
desired operating frequency within the Amateur band.
2. Press the [ TUNE ] button momentarily to place the ATU
in the transmit line (no adjustment/tuning will occur
yet). The " " icon will appear in the display.
Q P :
UICK OINT
The momentary press of the [ TUNE ] button will turn
the tuner on, and the microprocessor will automatically
select the tuning point closest to the current operating
frequency.
3. Press and hold in the [ TUNE ] button for one second to
begin automatic tuning. The transmitter will be en-
gaged, and the "
is in progress. When the optimum tuning point has been
reached, the radio will return to receive, and the
" " icon will again glow steadily (instead of
blinking).
4. To disconnect the ATU from the transmit line, press
the [ TUNE ] button momentarily. The "
will turn off, confirming that the ATU has been turned
off. In the "Off" mode, the transceiver will be directly
connected to the coaxial cable connected to your an-
tenna, and will operate based on whatever impedance
is present at the station end of the coax.
A :
DVICE
The ATU circuit is located between the final amplifier and
the rear-panel antenna jack; reception is not affected by
the ATU.
Page 58
A
UTOMATIC
ATU O
" icon will blink while tuning
" icon
A
NTENNA
PERATION
[ TUNE ] Button
Q P :
UICK OINTS
As shipped from the factory, only one ATU alignment point
is saved on each Amateur band. This was memorized dur-
ing the final alignment and performance verification stages
on the production line.
N :
OTE
Please check the operating frequency before beginning the
tuning process, to be sure you are not interfering with oth-
ers who may already be using the frequency.
T :
ERMINOLOGY
Antenna Tuner Memories: The microprocessor of the ATU
makes a note of the positions of the tuning capacitors and
the selected inductors, and stores the data for each 10 kHz
window in which tuning has occurred. This eliminates the
need to re-tune every time you return to a frequency on
which you have already completed the tuning process.
FT-950 O
T
UNER
M
PERATING ANUAL