Yaesu FT-450 Operation Manual page 91

I
NSTALLATION OF
A
UTOMATIC
Notes
The ATU-450 and ATAS-120A Active Tuning Antenna System cannot be connected at the same time.
The carrier signal transmits continuously while tuning is in progress. Please check the operating frequency
before beginning the tuning process. Be sure you are not interfering with others who may already be using
the frequency.
It is normal to hear the sound of the relays while tuning is in progress.
If the ATU-450 does not tune (the "
switch within the amateur band, it may be because the antenna or its coaxial cable have a serious problem
(very high or low impedance due to an "Open" or "short" circuit condition. Please check the antenna and
coaxial cable if this happens.
The ATU-450 only adjusts the impedance presented to the transceiver at the station end of your coaxial cable
feed line. It does not "tune" the SWR at the antenna feed point itself. When designing and building your
antenna system, we recommended that every effort be made to ensure a low SWR at the antenna feed point.
Do not connect an antenna or feed cable that is not designed for 50-ohm impedance.
The impedance matching range of the ATU-450 is from 16.5 ohms to 150 ohms (up to 3:1 SWR). Accord-
ingly, the ATU-450 should not be expected to match "long wire" type antennas unless you have taken specific
design steps to ensure that the impedance presented to the FT-450 is within this specification.
FT-450 O
A T
NTENNA
" icon does not blink) even though you have pressed the [ TUNE ]
M
O
PTIONAL
ATU-450 O
UNER
A
CCESSORIES
PERATION
Page 89