FT-2000
Operating Manual
Vertex Standard Co., Ltd.
60
“AUTO” mode.
Pressing the [AGC] button allows selection of the desired 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 selections are:
Operation
Mode
AUTO
AGC
Selection
LSB
SLOW
USB
SLOW
CW
FAST
AM
FAST
FM
FAST
RTTY
SLOW
PKT(FM) FAST
PKT(LSB)
SLOW
Advice: If the AGC receiver-recovery time is set to the “Off,” the S-meter will no longer
deflect. Additionally, you will likely encounter distortion on stronger signals, as the IF
amplifiers and the following stages are probably being overloaded.
Quick point: Several specs of AGC performance may be configured 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
Terminology: Automatic Gain Control, or AGC, is a circuit that senses the incoming
signal strength, and then limits 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 signal level.
SLOPED AGC Operation
In traditional AGC systems, the audio output from the transceiver becomes essentially
fixed once the threshold for AGC action is reached (usually several dozen dB above the
no-signal noise floor). The FT-2000, however, includes an innovative Sloped AGC
system on the Main band (VFO-A) receiver, that allows the audio volume to rise and
fall slightly according to signal strength. Although the rise/fall are not dramatic, they
