Antenna Tuner Memory System - Yaesu FT-857 Operation Manual

T O
RANSMITTER PERATION
FC-30 A A T O
UTOMATIC NTENNA UNER PERATION

Antenna Tuner Memory System

The FC-30, working in concert with the FT-857, 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 fre-
quency 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-30's memory system:
Tuning data is stored when you make an active effort to store it by pressing and holding in
the [ A ]( TUNE ) key for one 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 [ A ]( TUNE ) key for one second. This allows you to store your favorite operating fre-
quency areas into tuner memory without tying up memory space with matching data on
seldom-used frequencies.
If the FC-30 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 [ A ]( TUNE ) key again for one
second, as slight changes in the reactance may allow a match to be obtained. Then go back
to the original frequency and try again.
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-30. This will change the impedance
transformation taking place in the coaxial cable, possibly moving the impedance presented
to the FC-30 into an acceptable range. Note that this is not changing the actual antenna
SWR, but only the impedance "seen" by the FC-30's matching circuits.
If your antenna system presents an SWR of less than 1.5:1, you may wish to turn off the
antenna tuner, as full transmitter power will be delivered to the antenna system without
intervention by the FC-30.
If the impedance encountered by the FC-30 exceeds 3:1, and the "HSWR" icon is illumi-
nated, the microprocessor will not retain the tuning data for that frequency, as the FC-30
presumes that you will want to adjust or repair your antenna system so as to correct the high
SWR condition.
72 FT-857 Operating Manual