Yaesu FT DX 3000 Operating Manual

Also see for FT DX 3000: Operating manual Operating manual Operating manual Operating manual Operating manual

Contents

Page 60 FT DX 3000 O peraTing M anualAgc (A utoMAtic gAiN coNtRol)The AGC system is designed to help compensate for fading and other propagation effects. The AGC characteristics canbe individually set for each operating mode. The basic objective of AGC is to maintain a constant audio output levelonce a certain minimum threshold of signal strength is achieved.Press the [AGC] button repeatedly to select the desiredreceiver-recovery time constant. You will observe theAGC status notation in the AGC column of the BlockDiagram Display on the TFT display, denoting the AGCreceiver-recovery time currently in use. For most opera-tions, we recommend the “AUTO” mode. Additionally,you may disable the AGC by pressing and holding in the[AGC] button for one second.TOOls FOr cOMFOrTaBle anD eFFecTive recepTiOn[AGC] ButtonN ote: The “AUTO” selection mode selects the optimumreceiver-recovery time for the reception mode.In this case, the selected receiver-recovery time inthe AGC column of the Block Diagram Displayglows yellow (Normally glows Blue). Pressing the [AGC] button allows selection of thedesired receiver-recovery time constant. Normally,the “AUTO” selection is satisfactory for most situ-ations, but in the event of operation on a crowdedband where you wish to receive a weak signal, youmay wish to change the setting to FAST. The AUTOmode selections are:A dvice : The AGC selection will be memorized independentlyon each VFO stack of VFO-A and VFO-B. If the AGC receiver-recovery time is set to “Off” bypressing and holding in the [AGC] button, the S-meter will no longer deflect. Additionally, you willlikely encounter distortion on stronger signals, as theIF amplifiers and the following stages are probablybeing overloaded.QuicK poiNt:Several aspects of AGC performance may be configuredvia the Menu. However, because AGC can have such aprofound impact on overall receiver performance, wegenerally do not recommend any changes to the AGCMenu selections until you are thoroughly familiar withthe performance of the FTDX 3000.teRMiNology:Automatic Gain Control, or AGC, is a circuit that sensesthe received signal strength, and then limits the gain ofthe RF and IF stages to keep the output audio volume ata more-or-less constant level. AGC also protects the RF,IF, Audio, and DSP stages from overload, as it limits thesignal strength that is allowed to flow, irrespective of theinput signal level.Auto Agc SelectioNSLOWFASTMIDopeRAtiNg ModeLSB/USB/AMCW/FMRTTY/DATAblocK diAgRAM diSplAyIndicates the AGCSLOPED AGC OperationIn traditional AGC systems, the audio output from the transceiver becomes essentially fixed once the thresholdfor AGC action is reached (usually several dozen dB above the no-signal noise floor). The FTDX 3000, however,includes an innovative Sloped AGC system on the Main band (VFO-A) receiver, that allows the audio volumeto rise and fall slightly according to signal strength. Although the rise/fall slope is not dramatic, it is sufficient toallow you to use your ear to discern and separate signals according to signal strength, not just audio frequency.Using Sloped AGC1. Press the [MENU] button to engage the Menu mode.2. Rotate the [CLAR/VFO-B] knob (or press the p/qbutton) to select Menu item “004 AGC SLOP”.3. Press the [SELECT] button, then rotate the [CLAR/VFO-B] knob (or press the p/q button) to change thesetting to “SLOPE”.4. Press the [SELECT] button, then press the [MENU] but-ton to lock in the new setting and exit to normal opera-tion.You will now be using the Sloped AGC system.SLOPEDNORMALInput SignalAudio Output