Page 2 FT-450D OPERATION MANUALPHONESKEYFRONT P ANEL B UTTONS AND K NOBSPHONE JackA 3.5 mm, 3-contact jack accepts ei-ther monaural or stereo headphoneswith 2 or 3-contact plugs. When a plugis inserted, the loudspeaker is dis-abled.NOTE:When wearing headphones, we rec-ommend that you turn the AF GAINlevels down to their lowest settingsbefore turning power on, to minimizethe impact on your hearing caused byaudio “pops” during switch-on.KEY JackThis 3.5 mm, 3-contactjack accepts a CW key orkeyer paddles (for thebuilt-in electronic keyer),or output from an externalelectronic keyer. Pinout isshown below. Key up is 5volts, and key down cur-rent is 0.5 mA.DSP ButtonThis button selects the DSP functions.Available selections are CONTOUR,NOTCH, DNR, and WIDTH.IPO/ATT ButtonThis button selects the IPO or ATT feature. Available se-lections are:ATT:OFF/IPO:OFF ATT:OFF/IPO:ON ATT:ON/IPO:OFF ATT:ON/IPO:ON ATT:OFF/IPO:OFFIPO: OFF, ATT: OFFAttenuator is OFF, and the RF preamplifier amplifiesthe incoming signal.IPO: ON, ATT: OFFAttenuator is OFF, and the received signal bypassesthe RF preamplifier, yielding a direct feed to the firstmixer.IPO: OFF, ATT: ONThe received signal is reduced by 20 dB, and the RFpreamplifier amplifies the incoming signal.IPO: ON, ATT: ONThe received signal is reduced by 20 dB, and the in-coming signal bypasses the RF preamplifier, yielding adirect feed to the first mixer.The selection will be indicated in the Block Diagram onthe display.ON/OFF ButtonPress and hold in this button for one secondto turn the transceiver on or off.NB ButtonThis button turns the IF Noise Blankeron and off. Press this button to re-duce short-duration pulse noise.AGC ButtonThis button selects the AGC characteristics for the receiver.Press and hold in this button for one second to disable theAGC (for testing or weak-signal reception).Do not use the plug except the 3.5-mm 3-pin type plug. If the plug in correct size isnot used the radio may be harmed or damaged.