Yaesu FT DX 9000MP CONTEST - DATA MANAGEMENT..., Operation Manual

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Page 80 FT
DX
9000MP O
PERATION
M
ANUAL
AGC
(
A
UTOMATIC
G
AIN
C
ONTROL
)
The AGC system is designed to help compensate for fading and other propagation effects, with characteristics that can be
of particular value on each operating mode. The basic objective of AGC is to maintain a constant audio output level once
a certain minimum threshold of signal strength is achieved.
M
AIN
B
AND
(VFO-A) AGC S
ELECTION
Rotate the Main (VFO-A) band’s [ AGC
] switch to select
the desired receiver-recovery time constant. For most op-
eration, we recommend the “AUTO” mode.
S
UB
B
AND
(VFO-B) AGC S
ELECTION
1. Press the Sub (VFO-B) band’s [ RX
] switch to engage
Dual Receive operation.
2. Rotate the Sub (VFO-B) band’s [ AGC
] switch to se-
lect the desired receiver-recovery time constant.
Rotation of the [
AGC
] switch allows selection of the de-
sired receiver-recovery time constant. Normally, the
“AUTO” selection is satisfactory for most situations, but
in the event of operation on a crowded band where you
wish to receive a weak signal, you may wish to change the
setting (to FAST, for example). The AUTO mode selec-
tions are:
Operation Mode AUTO AGC Selection
LSB SLOW
USB SLOW
CW FAST
AM FAST
FM FAST
RTTY SLOW
PKT(FM) FAST
PKT(LSB) SLOW
TTTTT
OOLS OOLS
OOLS OOLS OOLS
FOR FOR
FOR FOR FOR
C C C C C
OMFOR OMFOR
OMFOR OMFOR OMFORTTTTTABLE
ABLE
ABLE ABLE ABLE
AND AND
AND AND AND
E E E E E
FFECTIVE FFECTIVE
FFECTIVE FFECTIVE FFECTIVE
R R R R R
ECEPTION ECEPTION
ECEPTION ECEPTION ECEPTION
MAIN (VFO-A) [AGC] Switch
A A
A A A
D D D D DVICE VICE VICE VICE VICE
If the [ AGC
] switch is set to the “Off” position, the
S-meter will no longer deflect. Additionally, you
will likely encounter distortion on stronger signals,
as the IF ampligiers and the following stages are
probably being overloaded.
Q Q
Q Q Q
UICK UICK UICK UICK UICK
P P
P P P
OINT OINT OINT OINT OINT
Several spects of AGC performance may be con-
figured via the Menu. However, because AGC can
have such a profound impact on overall receiver
performance, we generally do not recommend any
changes to the AGC Menu selections.
T T
T T T
ERMINOL ERMINOL ERMINOL ERMINOL ERMINOLOGY OGY OGY OGY OGY
Automatic Gain Control, or AGC, is a circuit that
senses the incoming signal strength, and then lim-
its the gains of the RF and IF stages so as to keep
the output audio volume at a more-or-less constant
level. AGC also protects the RF, IF, Audio, and DSP
stages from overload, as it limits the signal strength
that is allowed to flow, irrespective of the input sig-
nal level.
SUB (VFO-B) [AGC] Switch
VDD TEMP SWR BIAS
A A
A A A
D D D D DVICE VICE VICE VICE VICE
When a received signal becomes degraded due to
pulse type noise, you may improve signal readabil-
ity by setting the
AGC HOLD TIME in Menu
Items AGC 002 , AGC 004 , AGC 006 , AGC 008 ,
AGC 010 , and AGC 012 to “0 msec”.