locked Re: WSJT-X Audio Output Reduces


Bill Mader
 

It is well-documented that using ALC to control power levels frequently creates IMD and its resultant  QRM.  ALC from a transmitter to an amplifier should be set and used to prevent accidentally over-driving the amplifier.

Using a dummy load, adjust TX audio levels so that ALC just begins to show.  You'll note that this level occurs when reducing TX audio begins to reduce power output.  That point prevents unnecessary splatter (IMD) regardless of the SSB mode.

I'm looking at an FT8 signal on 30m as I write this that is twice as broad as it should be and I'll bet the op's ALC is way too high.  Listen to 20m and you'll find all kinds of signals with over-driven ALC, many of them created by the ALC Voltage creating distortion in the amplifier to add to the distortion created in the rig.
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73, Bill, K8TE

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