Fldigi Transmit Output Levels; Step 1; Figure 46 Waterfall Controls - Kenwood TS-990S Configuring Manual

This display shows my settings on a quiet band. The -9 setting shows 9 dB of 'gain' (the more negative
the value, the higher the 'gain'), the 45 number relates to the 'dynamic range' of the display. Lower
numbers of 'dynamic range' will tend to 'compress' the signals into a narrower range of colors.
Experiment here for something you like.
At this point you are left with only one more set of adjustments – transmit audio settings, the next
section. You are on the home stretch!

Fldigi Transmit Output Levels

I deliberately left the most important adjustment for last so that you would be familiar with all of the
controls we have needed to adjust. By now you should be comfortable with how to access the sound
level adjustments in Windows and how the Fldigi interface controls some levels. There is a unique
method of setting the actual TS power as it pertains to the TS-990S. Knowing that we will likely use
between 10 and 25 watts TX power most of the time (high power is not needed for digital modes if an
RF path exists) and that data tone levels MUST be set a minimum of 13 dB lower than voice levels, we
will set the SSB voice power level (the PWR control) at about 70 watts (remember we will be using the
-13 dB level most of the time) and adjust the TX audio gain into the TS-990S so that we obtain NO ALC
INDICATION. Any ALC action due to the way ALC works is non-linear operation. Any non-linear
operation will distort our transmit signal making the IMD climb and making it more difficult for the far
end station to decode properly. A 'clean' signal at lower level is much easier to decode than a stronger
distorted one. Keep this in mind. A properly adjusted PSK31 signal will be transmitted in a little over 35
Hz of bandwidth. This is usually described as clean lines and narrow signal (on the waterfall display). This
properly adjusted transmit path is also not hard to obtain if you follow this method. Using this method
of adjusting the audio transmit drive, we will attempt to keep the audio level attenuator in Fldigi to
between 0 and -3 dB for our adjustments. This will give us about 3 dB of headroom so that we will not
need to perform this adjustment when changing digital 'modes'. Once you have mastered this method,
it applies to any transceiver used in digital modes.

Step 1


Set the TS-990S transmit power (PWR control) to 75 watts.

Set the METER on the TS-990S to read 'ALC'.

Set the Fldigi 'base level' attenuator value to 0 dB.

Figure 46 Waterfall Controls

Configuring the TS990S for Fldigi
Tutorial by Mitch Baum – AE2A
Page 44