Yaesu FT DX 9000MP CONTEST - DATA MANAGEMENT OPERATION Operation Manual - Agc (A

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”.