Tuesday, 5 May 2015

Adjusting ALC on the FT-450D

The ALC meter on the FT-450D is a little confusing. The manual is not much help either. However I think I have worked out how to set the levels with an soundcard connected to the digital data socket on the rear.

Your setting will be different than mine but here is how I set mine.

I am using the DM780 module of Ham Radio Deluxe to operated the digimodes. The output of a cheap sound card is connected to the rig via a dedicated data lead.
  • Set the rig at 35 watts power output
  • set the rig to D TYPE
  • Set this to USER-U and exit
  • Tune the rig up to a digimodes frequency (21.070 MHz for instance) on USB Data
  • Press the F key for more than one second to enter MENU mode
  • Rotate the DSP/SEL knob until D TYPE appears
  • Press the DSP/SEL button

  • Rotate the DSP/SEL knob until USER-U appears
  • Press the DSP/SEL button
  • Press and hold the F button to exit MENU mode
You can also do this from DM780

  • Set the output of the sound card to around 25%

  • Set the audio frequency in the waterfall to around 1 KHz
Set the audio frequency in the waterfall
  • Now transmit a digital CQ (Use PSK-31) and adjust the soundcard transmit level slider (from DM-780) until the ALC level on the rig is just just barely showing above 0
DM780 TX adjust slider


You will then be transmitting at optimum levels, no risk of overloading the input stage, no risk of frying the PA stages and most importantly no spatter around your transmit frequency.

Note that as you change the audio frequency that you are transmitting on say 2.5KHz you may have to alter the gain slightly;

1 comment:

  1. Thanks, im struggling to get my 450 to do digimodes. Doesnt help that im Foundation level so dont have a lot of experience yet, just trying things to see if I like them!

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