Yaesu FT-100D Operating Manual page 69

FC-20 Automatic Antenna Tuner Operation
ANTENNA TUNER MEMORY SYSTEM
The FC-20, working in concert with the FT -100, can store impedance matching data in its
micro-computer memory, so as to provide instant adjustment as you transmit in different
areas of a particular band. A total of 100 memories are provided: 11 of these are "general"
memories apportioned one per band, while the remaining 89 are allocated for specific
frequency data within the various bands, with the capability to resolve new tuning data
every 10 kHz. A few guidelines should be noted regarding the FC-20's memory system:
I. Tuning data is stored when you make an active effort to store it by pressing and holding
in the [B](TUN) key for
Y:,
second. Although the tuner will automatically activate itself
if it encounters more than 1.5: 1 SWR, this memory will not be stored unless you have
pressed the [B](TUN) key for
Y:,
second. This allows you to store your favorite operat-
ing frequency areas into tuner memory without tying up memory space with matching
data on seldom-used frequencies.
2. If the FC-20 cannot resolve a satisfactory match because the SWR is above 3: 1 (2: 1 on
the 50 MHz band), the tuning process will stop, and no memory data will be stored.
However, you may wish to move frequency a few kHz, then press the [B](TUN) key
again for
Y2
second, as slight changes in the reactance may allow a match to be ob-
tained. Then go back to the original frequency and try again.
3. Another technique which may allow matching in some situations is to add a few feet or
meters of coaxial cable on the "antenna side" of the FC-20. This will change the imped-
ance transformation taking place in the coaxial cable, possibly moving the impedance
presented to the FC-20 into an acceptable range. Note that this is not changing the
actual antenna SWR, but only the impedance "seen" by the FC-20's matching circuits.
4. [fyour antenna system presents an SWR of less than 1.5: 1, you may wish to tum off the
antenna tuner, as full transmitter power will be delivered to the antenna system without
intervention by the FC-20.
' : :::1:::"
5. [fthe impedance encountered by the FC-20 exceeds 3: I, and the "HI SWR" ; " ... '
! ....... .
icon is illuminated, the microprocessor will not retain the tuning data for that
frequency, as the FC-20 presumes that you will want to adjust or repair your
~ : : ;
td!?
"'HI SWR"
antenna system so as to correct the high SWR condition.
ICON
FT-JOO
MICRO MOBILE OPERATING MANUAL
67